Prob the abs module working the system. You know for certain what wheel it is coming from? I believe the abs light will come on if the system gets activated. If it stays on when everything is normal, then a prob has been detected and the system has been shut off, you have normal braking, the abs has been turned off. If you have access to a scanner, check for current/history codes. Could be a faulty wheel speed sensor giving bogus readings to the pcm/abs module (happened to me once) could be a faulty abs module, could be a programming error. If your car is still in warranty, they should check it out at no charge. Maybe this can at least point you in a direction.
Later