like to see if this is normal, i have a 2005 envoy xl. love it but one thing i have notice about the brakes. i was driving about 40mph on a bumpy road when i hit the brake pedal, as i did a loud noise sounded like my brake paps was going to fall off and the pedal felt like it lost its resistent. i ask some friends and they told me it could of been the anti-lock kicking in. can someone tell me if this is the case?