Vine: Gronk held in the endzone, flag thrown, later picked up

Someone care to explain how this wasn't a foul?

On the Patriots final play with three seconds remaining, Rob Gronkowski was held in the endzone, a flag was thrown but later picked up. If the flag held up it would've been an untimed down for the Patriots at the Panthers goal line.

Instead, the game was over with the Patriots the loser.

Judge for yourself. Was this a foul?