The call you are talking about where the kicker took a half step before the ball was snap may have been valid, but speaking with some experience, more than likely, no single official was watching both the kicker and the snap in a scrimmage kick formation. The referee is strictly watching the kicker and at a wider angle than normal so he can watch the kicker. The Linesman facing the holder is watching strictly the holder and the opposite linesman is watching the ball and the entire neutral zone (or the referee has both the holder and kicker and the two linesman split the neutral zone at the ball). The umpire is watching the snapper and the offensive line, as well as the defenders right over the ball. So more than likely, unless it was clearly obvious, that would have been tough to see. <div>
</div><div>A quarterback stepping early is easier to catch because the referee is not out as wide watching him, he's usually a few yards behind him opposite his throwing hand, so he can see the snap and the quarterback at the same time. </div>