So it is an all of a sudden grab?
If you let off a little bit, do the brakes let off as well? Or do you still feel them slowing you down?
Basically what I would check for is to see if they are just grabby, so if you let off back up into what you think is the take up 1/4 pedal and you have no brakes like when you were pushing down, then I might agree.

If however when you let off, the car still slows down and the brakes are engaged, then my bet is the interal valve that "breaks" when you push the pedal down is sticky and suddenly gives causing what feels like grabby brakes.