Factory and quality aftermarket rotors really don't warp persay. It's either a build up of friction material on the rotor surface, rust or dirt build up behind the rotor on its mounting surface or improperly torqued wheel, which would really only apply to cars and sssa with lug nuts. Pull the rotor off make sure the mounting surfaced are clean, retorque the rotor and do 8-10 very very hard stops with riding long enough to allow the rotor to cool back down between each time you do it. Also do not drag the brake, and if you're sitting at a stop light after quick braking don't hold the brake either.