I could see the open space between Preator and the receiver close before the ball got there. It was a big call and really hurt - but the refs got it right.
Imagine a camera from the middle of the end zone. The angle would show the space between the two players. The space closed, then the ball got there. The angle linked above makes it hard to tell when contact between the players happened.
But, I think it's pretty obvious that the refs missed this taunting penalty. Compared to the penalty they gave our team earlier in the game, it seems that if they intended to be consistent that this definitely deserved a flag.