09 S coupe 8k easy miles- a definative groove in the middle of the outside of the rear rotor. Remaining three rotors have no sign of this issue. Anyone else seen this-cause and fix?? Got an appointment Thursday with the dealer and wonder if this is a potential warranty issue???? or am I gonna have to pony up and eat it?

 

dealer
should adress this problem

 

I got the groove after running the car hard, interesting that its only 1 grooved disc on your car tho.

 

Grooves like that typically happen when something gets lodged between the pad and the rotor. All it takes is a very small pebble to find it's way in there.