When i stop my car, just before it comes to a full stop i hear a noise that sounds like a spring releasing, and at the same time the brake pedal pushes back against my foot, but then the car stops fine. Anyone have any ideas what this is? When i bought my car i bought drilled/slotted rotors, semi-metallic pads and s/s braided lines, but i haven't installed them yet as i'm waiting for the pads that are on it to wear out. Is this noise a sign that it's ready for the upgrade? All help is appreciated. Marc