Deep grooves will most likely have to be machined out (turn the rotors).

 

Actually I contacted StopTech about this and they said grooves are very common with drilled rotors, and don't necessarily indicate a problem. They said if there is vibration noticed while driving (which there's not), turning the rotors would be the next move.

He recommended I check the pads for wear ASAP and if they look fine - then to just give them a few good bedding cycles to see if that helps with the squealing. If necessary, however, the pads may need to be replaced (it's been almost 15K) even though I don't drive too aggressively.

Thanks for the info. I'll keep you guys posted!

-B