ABS Brakes/Wheel sensor ???

On a 2001 Tahoe with 62,000 miles , sitting at stop light with brake applied, engine shutters a little and brake petal just depresses down halfway from where it was at. Problem has not duplicated again at this point. New ABS module replaced a few months back. These vehicles are prone to ABS and wheel sensor problems as I see. Just throwing problem out, maybe someone had similiar problem and could point in the direction of problem and repair.