"We play so many games nowadays compared to, say, Shane Byrne who reached the 100 cap landmark first a few years back, but it's still an important honour for me and it's a nice one to get," Cullen admitted.
'I remember the early days and before I made my competitive debut, I would have spent a lot of time on the bench. This was back in the day when there would often be a full front row amongst the replacements.
"Because I had played a lot of my underage rugby in the back row, I would have been seen as more of a utility forward. I made my debut in a friendly away to the Borders and a month later I came on for Victor Costello against Connacht at the Sportsground in Galway in one of my earlier games, it did mean an awful lot to me. And it still means the same every time I pull on the shirt.
"I made my first European start in a heavy loss away to Stade Francais alongside the likes of (Blackrock College school-mates) Ciaran Scally and Peter Smyth, so in those early days you just take whatever you can from experience and build on it. That was a massive learning curve for me personally."
Asked to recount some highlights from his Leinster career to date, the towering lock added: "Winning the Celtic League, as it was called back then, is hard to top. There was so much hype around the game at the time and obviously the manner of victory that day will always be a pleasing memory. I would have made an assumption back then that after that win we would go on to lift more silverware, but that obviously hasn't been the case.
"You look back and wonder about the highs and the lows and wonder where it might have gone wrong. In that respect, I would say that Leinster has probably under-achieved over the years."
Cullen is determined to make up for Leinster's lack of silverware by aiding the province in their quest to annex the Magners League crown in the coming weeks - starting on Saturday with the trip to the Scarlets.
"To win on the road, be it in the Heineken Cup or in the Magners League, is tough. On Saturday we will need to be ready for a dogfight and be streetwise because they have a very good record at home. Llanelli is a classic rugby environment.
"I faced them last year and they were probably the form team in Europe at the time. Their support that day was incredible and out of all of the grounds in Wales, Stradey probably holds the most tradition. They're a very proud club so we will need to be disciplined," he conceded.
"We will be conscious of the defeat we suffered earlier this season and though that day still hurts, you have to respect the ability of any side that can do that to you. Since then our form has been good in the league.
"We won well in Cardiff and perhaps caught the Ospreys on a good day and followed that up with a good win in Cork against Munster. More recently we really dug deep to win in Connacht."
On how Leinster will approach the title run-in, Cullen views it as very much a 'one game at a time' attitude.
"Competition is really strong in the squad with players coming back from injury and we're all pulling in the same direction. Discipline is really important at this time of year.
"Our form this season on the road has generally been consistent. It is a cliché, but we have to focus on every game individually from here on in."