I had problems with warped rear rotors on my LC I changed them about 5000 mile ago, and now have the same problems again, I can feel the brake pedal move slightly up and down on slow braking and also had the rear right hand side wheel off the other day, and when I rotated the rotor, I could hear the disc rub on the pad at a certain spot, indicating that the disc has warped, can anyone suggest why it should happen again so quick.