The more I look at it the more I think it was a bull**it call. It starts at 23:57 and you really have to watch it like the Zapruder film second by second. Sorry I don't know how to isolate it.
1. The announcers don't know the rule.
2. Is the distance between Caleb's feet at the start three feet? I think so. He starts with his right foot on the ball logo and his left foot on the A. When he finishes his left foot is on the logo. Is that more than three feet??? Remember he only needs to have a part of a foot inside that three foot window. If it is it has to be by an inch or two. It's not a blatant call so at that point of the game you don't call it.
3. Finally, the official never looks down. How does he know where the play started? You don't make a game changing call on a guess.