I had a front caliper seize last week, and it warped the rotor, too, so I wound up buying a new rotor in addition to the new caliper. Unfortunately, it happened about 100 miles from home. I had just replaced the pads and rotors 3 months ago. I even flushed the system. "It just happens" they said. 120k on the car, so no warranty. Yes, I'd second that idea about visiting the dealer if it's still under warranty!