NFL Rules: basic question about false start

According to Section 4 Article 2 if the player moves "in such a way as to simulate the start of a play" it is a false start. There are also two other items that are exceptions to Article 2 relative to interior lineman.

I would assume the the player was judged to have moved in a way that does not simulate the start of a play or the officials just missed it. It is a judgement call on the official.

Zarathustra, thanks for the answer.

No problem. There are a LOT of nuanced rule in the NFL. The occasional major blunder on a call just reminds me how good a job these (now) par-timers really do.