Are you insane? The referee clearly says "21", not 29. And just for good measure, #21 walks in front of the referee right after he says it.
Watch the replay: http://www.nfl.com/videos/chicago-be...that-never-was
It's hard to see, but #21 flashes on the screen at the 1-2 second mark, and you can see he's clearly gotten beat by the man he's responsible for, and he tugs at the guy's jersey. You can actually see the player's shoulder tip due to the hold.