Center movement

[Refburn]

I have a question, how much movement do you allow on a center when he is snapping to a QB in a shot-gun (less than 7 yards back).
I saw a championship game this week where the center had his head between his legs looking back as the team was set and QB calling signals. He then brought his head up abruptly looking forward then snapped the ball (not a continuous motion). It was really obvious and stood out seeing that much movement before the snap along the line. Also many times it happened as the QB lifted his leg really high to signal a player to go in motion. There was never a false start or motion called.

I have coaches routinely chirping in my ear for the smallest butt wiggle wanting a flag.
Am I missing something here?