I had new rotors and brakes installed on July 29, 2008. I did the normal break in routine, by braking lightly. I have about 1600 miles on the new rotors and brakes. When I brake hard, I notice a grinding vibration. Do you think the pads are offset? When I don't brake hard, it everything is normal. It's just once in awhile you have to brake hard cause someone cuts your off, etc...Any thoughts? Thanks!