Unnatural football move was the call. Here's the rule.
Rule 7-1 Article 5
a. After the ball is ready for play and before the ball is snapped:
4.[Defensive] Player(s) aligned in a stationary position within one yard of the line
of scrimmage may not make quick or abrupt actions that are not part
of normal defensive player movement in an obvious attempt to
cause an offensive player(s) to foul (false start). An official shall
sound his whistle immediately [S7 and S21].
I think in Alabama they are real picky when it comes to interpreting "unnatural" acts.