Ex–Nina Ricci designer Olivier Theyskens was coy at the Costume Institute Gala when we asked if he’s taking over design duties at Halston, as rumored. “Oh God,” Theyskens said. “These are rumors.” So the rumors have no basis in fact? “These rumors — I have to live with that,” he said cryptically, laughing. Does he want to go to Halston, should the offer come through? “Oh, this I don’t know. Really. It’s really something I don’t know,” he told us, and fluttered away.