This isn't really surprising at all. I'm more surprised by the fact that sound engineers didn't play the track at the appropriate time. She's so slick with her lipsyncing. I listened to the televised version, and the lipped part has vocal strain and everything and sounds completely different from the studio version. If I hadn't seen this video, I probably wouldn't have even known she lipped that part haha
She has got to be one of the least professional "professional" singers out there. It's staggering how inept and clumsy her live performances are these days.