First Time I've seen this

[NorCalMike]

Working U in a varsity game. 4th and 3. Team A QB using a hard count. Nose guard steps up on the hard count. His foot touches the ball. I blow whistle and drop my flag. I expect to flags from at least one of the flanks but neither one threw their flags. They are looking at me like I am crazy for throwing a flag on defense movement. I almost started to doubt myself but I know his foot touched the ball. Not sure how he could do it with out going over the line.  It was definitely different.

[mbyron]

Since the NZ starts with the nose of the ball, it's not possible to touch the ball without encroaching. Good topic for halftime or postgame.

[busman]

And that is one instance where the U might have the only view of the encroachment, so flag it.  It is one of the exceptions to the mechanic.