Cullen glad Leinster 'got over the line' in Champions Cup semi-final thriller
When Ireland wing James Lowe completed a hat-trick of tries early in the second half, Leinster were in command at 20-3 ahead and seemingly cruising to a third successive Champions Cup final.
But with Ross Byrne missing several goal-kicks,the mood among a capacity crowd of over 82,000 became increasingly nervous as English Premiership leaders Northampton scored 14 unanswered points through converted tries from George Hendy and Tom Seabrook.
Having been in complete control, four-time European champions Leinster -- based across Dublin at Donnybrook - led by just three points with six minutes remaining and it needed a turnover by skipper Caelan Doris and Jack Donan in the closing seconds to make sure of victory.
For Leinster, beaten in the past two Champions Cup finals by La Rochelle it all threatened to be a repeat of last season's showpiece match when they let slip a 17-point lead against the French side.
But instead they will now face the winners of Sunday's match between five-time European kings Toulouse and Harlequins in a May 25 final at London's Tottenham Hotspur Stadium.
This was the first senior rugby match played at Croke Park, the headquarters of Ireland's Gaelic Athletic Association, since 2010.
"It was an amazing occasion, wasn't it?," said Cullen. "Certainly, we got 80 minutes of entertainment, a little bit too exciting maybe at the end."
He added: "The score goes to what, 20-3. Then I suppose there's a human nature part to it. You can try and sit and protect what you have...We maybe struggled with that a little bit, but credit to Northampton.
"We dug in there at the end and we're delighted to get into another final.
"The most important thing is you get over the line, and we managed to get over the line thankfully."
Lowe's tries owed much to the quick thinking of fellow Ireland international Jamison Gibson-Park, with the scrum-half sending the flyer in for his first score with a superb long pass off a sharply tap penalty.
"A lot of players, not to talk myself up, but they've all played with me long enough now to know I'm going to be looking for those sort of opportunities," said Gibson-Park.
'Standard bearers'
As for the prospect of facing either Toulouse or London club Harlequins in the final, Cullen said: "Toulouse are the standard bearers of the competition really.
"You could see the set-up they had when the game went professional first. They were light-years ahead of us, let's be honest. We sort of feel that we've been chasing them every since.
"Quins are similar to Northampton they have really strong attacking intent and they’re just a constant threat."
Northampton captain Courtney Lawes admitted to mixed emotions, with the former England back-row saying: "We made a lot of mistakes and you can't win at the highest level if you do that.
"But on the plus side we were able to push one of the best teams in the world."