Understandable. It nevers happen under light to moderate braking. It only grabs when the ABS system has to activate. It is my understanding that the ABS system only activates when deceleration occurs at a higher rate than what the normal hydraulic system can control. The best way to test your theory is to open the bleeder valves at the caliper and/or control unit. Deterine from that if it's a mechanical or hydraulic problem. BTW I just bought the car a month ago in Boston. I looks like the previous owner replaced the brake fluid w/ ATE super blue. Whether or not he flushed out or just loosened debris or corrosion, I'm not sure. And how long ago is another question.