Credit: Jeffrey Mayer/WireImageJeffrey Mayer/

Is fame going to Heidi Montag's head?

Hills vixen Kristin Cavallari seems to think so.

"She changed her number, so I can’t get a hold of her," she tells E!'s The Daily 10. previously reported that at a recent MTV photo shoot the 23-year-old Montag -- who is now campaigning to be the blonde Tomb Raider after landing a cameo in an Adam Sandler movie -- showed up with four bodyguards and refused to pose with her other Hills castmates.

"No one saw her because no one was allowed to speak to her," Cavallari, 23, tells E!. "She didn’t take the group photo with us which was really disappointing."

She did have one piece of praise for Montag, who famously underwent 10 plastic surgery operations in one day: "Honestly, Heidi looks better in person."

The final season of The Hills begins Apr. 27 -- and it could go longer than expected. "They could order 12 more episodes, and it is still the same season," Cavallari says.

How would she feel if frenemy Lauren Conrad returned?

"I hope Lauren comes back," she says. "I think it would be awesome if she comes back."