2004 Pontiac Grand Prix Brake pedal pushes back

My brake pedal, with the car fully stopped at a light, at times makes a noise similar to the ABS system resetting itself and pushes back, as if attempting to free the car to move. This happens intermittently. I had the front struts replaced a few weeks ago and am suspicious that perhaps when the front end was put back together that a brake connection may be loose, or perhaps that the ABS sensor may be loose or worse going bad. Any ideas?