Moon hit his century in the 39-38 Premiership Rugby Cup defeat at Bristol Bears on Saturday afternoon.
It wasn't the result he would have hoped for on his big day, but the lock was still able to happily reflect on a special week and a special achievement.
"It's taken me a while!" Moon said when asked about getting to 100 games for Saints.
"I didn't really play for the first three years so I look at it and think I've played 100 matches over the past five years.
"I went through it the traditional way, playing National Two, National One, the Championship, did a small stint in Australia on loan and then came back and played my way into the first team from there.
"I've probably actually played 200 or 300 games of rugby but only 100 for the first team so far.
"The guys made it real special in the week and it was a really good week for me, result aside.
"Everyone put their arm around me, shaking my hand and congratulating me so it's been awesome.”
Academy graduate Moon made his Saints debut in a cup clash with Newcastle Falcons back in November 2016.
He has also previously played for clubs such as Cambridge Rugby and Australian outfit Randwick DRUFC.
"I'm proud of that route I've had to take," said the 27-year-old.
"A lot of guys who are in my position have sort of hit the ground running from a young age, but for me I had to grow into my body.
"I've always been a big freak so it probably took me until I was about 21 or 22 to really figure out how to use my body.
"I used to go on the field and get told all the time 'you're a big bloke, why are you not using your frame and throwing yourself around a lot?'.
"It took me time to figure that out and last year was the best I've really been able to figure it out.
"It's been a long road but it's made it all the sweeter."
Moon enjoyed a hugely impressive campaign in 2022/23.
And he says he has been working hard during the off-season to make this an even better year for him.
Moon said: "I worked hard in the off-season, although it's not like we've got a really long off-season. You've got five weeks to work on stuff but you're also trying to get some rest in there.
"I went pretty hard at it. I saw a couple of areas I needed to be better at, like my ball carrying and my leg drive has got to be better.
"I tend to get quite high in the carry so I've been working on my leg strength and stuff like that.
"It was about identifying a couple of areas and then it was nice to see that stuff I'd worked on by myself helped coming into pre-season.
"I'm still working hard and I feel very good.
"I've missed one week of training with a little niggle but other than that, I feel fresh.
Moon played almost 70 minutes on Saturday as he made his first appearance of the season.
But Saints were hit by a last-gasp Gabriel Ibitoye try as they fell to defeat.
"At this time of the year, you're looking for a performance - and I think that was another step up from the previous week," Moon said.
"It was a really strong Bristol side that we played, a Prem Bristol side, so to run them really close this early in the season with us changing a bit of philosophy in defence, we performed really well.
"The scoreline doesn't particularly reflect it and there's bits and pieces we need to work on ourselves but it was a decent performance.
"We are a performance-minded team because we've had results over the years where it looks really good on the scoreboard but we're actually really annoyed with ourselves because we've underperformed but the scoreline doesn't suggest that.
"Sometimes the scoreboard can kid you into a false sense of security.
"Games like Gloucester last year, the scoreboard looked good but we were actually really annoyed that we underperformed.
"This game here, performance wise it was a step up from the past few weeks, but we're all athletes, we all want to perform, compete and win everything we play in so that bit is annoying, but at least the performance was a step forward."
Though Saints shipped 39 points on Saturday, Moon believes the club is taking good steps to improve under the guidance of new defence coach Lee Radford.
"Radders, with his background coming in, our defence system has changed a bit," Moon said.
"Previously, we were just trying to put bodies on the floor and compete in that respect, but now, with Radders, it's a bit more holding guys up, keeping them in the air.
"Time in the tackle is a phrase we use all the time and it just gives our defensive line time to set.
"It's something that I personally love, being a strong, tall guy, because I get to hold people up, wrestle people, keep guys in the air and buy time for everyone else to get set so it means we can get off the line.
"It's a change of philosophy for us and it's going to take time. This is the fifth game of us doing it and we can see week on week, as we've installed that it's got a lot better.
"On the defensive side of the ball, albeit we conceded a bunch of points but the stuff we're really going hard at has improved."