It better not have been. If it was...not impressed.
Oh please, the lyric fits perfectly, it's hilarious. He's been changing the lyrics of CMAR around just a little since he started doing club shows and adding in a few lines from other songs. It used to be "You're So Vain" that he sang a few lyrics from.

Just enjoy the show and try not to let your love of Britney interfere with your appreciation of Justin and his show.