Audrina Patridge AudrinaNoLaurenVegas.jpg

Does this mean Lo has officially replaced Audrina as Lauren Conrad's closest pal?

Us reports that Patridge - who turned 23 on May 9th - celebrated her birthday this weekend in Vegas at club LAX without Conrad. Trouble brewing in the Hills?

"You fight, you make up, you get along," said Lauren at the season finale of their reality show last week. "Obviously we are going to have problems, but we are still friends and we love each other."

So are there really problems or is all this just to make us watch the show?