I recently rotated the wheels (front to back, back to front) of our 940. Soon afterwards I notice pulsing of the brake pedal and steering wheel shudder when stopping, mostly from highway speed. Previously, there was no pulsing or shudder. Driving at highway speeds produces no shimmy so I don't think the wheels are out of balance. I am wondering if the front rotors became warped in the process of rotating the wheels. The front rotors are original and have 205K miles on them. I did not measure the front rotor thickness but the rotors do show signifiant wear (no surprise considering the mileage). The rear rotors have been replaced and have about half that mileage--they do not appear to be excessively worn. I torqued the wheel bolts uniformly but I'm wondering if the combination of thin rotors and retorqueing may have warped the rotors. If that's not likely, what else could cause the brake pedal to suddenly pulse and the steering wheel to shudder?