Is Lindsay Lohan stalking Mary-Kate?

What’s the beef between Lindsay Lohan and Mary-Kate Olsen? Lohan was apparently on Team Mary-Kate when Olsen’s ex-boyfriend, Stavros Niarchos III left her for Paris Hilton. But could the recent rumors that Lohan did some “dirty dancing� with Niarchos at Element after his break up with Hilton have caused tension between the former friends?

Page Six is reporting that Lindsay endured some icy looks from MK at Monday night Costume Institute Gala at the Met. A source told the gossip column, "MK looked like she wanted to die when she saw Lindsay. She hung back and refused to get close…She clearly did not want to be near Lindsay and made an effort to not get close. It was odd."

Another insider claims it’s Lindsay’s semi-stalker behavior with regard to Mary-Kate that has the Olsen twin freaked. "MK is very suspicious of Lindsay,� the source claims. “Lindsay always e-mails her. She is always trying to find out from others who she is dating - MK thinks she's creepy."

Both the Lohan and Olsen camps deny the scoop. "As far as Lindsay is concerned, she has no problems with Mary-Kate," a flack for Lindsay said. Olsen’s people assert, "That is ridiculous. There were 15 other actors on the red carpet at the same time and it was hectic."