"Warped" brake rotors is that vibration you fell when you apply the brakes. This is usually caused by improper bedding in of the brake pads to the rotors, improperly torqued lug nuts, using your emergency brake on very hot brakes, resting your foot on the brake pedal after a hard braking session or a combination of the above.
For a full technical opinion of this issue, go to the Stop Tech website.