Unless on a rolling road or dti gauge set up visually you wont see a warpage(distortion).Most likely if when braking you feel the judder through the pedal it resorts to rear brake application.If the judderings felt through the steering wheel most definitly from front whether warped discs or wheel bearing failure.hope this helps get new rotors.
Jock the Haggis Basher yeehaa.!!!, September 2006