It does go in and out, and doesn't move around. It's only that one spot, if I look at the egg from the other side I can't see the shadow at all, and when I rotate it doesn't move. It's just a faint flutter, at first I thought maybe he was trying to get through the membrane and was lifting it up as he pushed but it's so rounded, not pointy.
OH GOOD, then that's just his big butt. LOL, Let me know when the due date is.