If she has KK then thats an interesting line. Most players would smooth call that flop, considering they should know you for KK (which if they hold KK, is now impossible) or AA...and holding KK would give them an almost outdrawable hand. I'm going to think AK here, AK can (and might depending on her style) reraise preflop, and since it seems she's betting to protect a hand almost on the flop, its possible she has that.