You know you're getting up there in Hollywood when you're mentioned in Page Six. So congrats, Chace Crawford -- you're hitting the big time. The Gossip Girl star was spotted snuggling up with American Idol's Carrie Underwood this past weekend, according to the gossip column. But the "All-American Girl" seems to have channeled the snooty Upper East Side 'tude along with her Gossip Boy -- "She was being rude and nasty," a spywitness laments.

Wonder what Blair has to say about that…