Quick question...I recently purchased a '10 Denali AWD and I get a slight pulse to the car, not the pedal, when braking at low speeds. I thought this was from warped rotors so I replaced the fronts. The pulsing is better but still noticeable at lower speeds. My question is this; could it be that the rear rotors may also be warped or is this a function of the AWD system? Thanks!