How is this not a flagrant foul?

In case you missed it, the Bulls/Celtics series had yet another overtime game last night. The Celtics prevailed, in no small part to Brad Miller missing the first of two free throws that would have tied the game. In his defense, his lip was bloodied by Rajon Rondo as he drove to the hoop. Miller caught the ball in the middle of the court and Rondo almost took his head off. It’s pretty clear he wasn’t going for the ball. Why wasn’t this called a flagrant foul?