Depends on how deep the grooves are. Slight grooves are normal and are nothing to be worried about. Deep grooves are a problem. Your local brake shop should be able to tell you if they are too deep for turning or not. If they are too deep, only then should you consider replacing them. Good luck...Sounds good. There are some grooves in the rotors...turn em or replace em?
Deep grooves do matter, especially when installing new brake pads. The grooves will be areas of the rotor that the brake pads won't make contact with, which can seriously hinder your braking power. It also makes the pads wear quicker due to all the force from the calipers being applied to a smaller surface area on the pads.Groves don't matter, warp, and thickness does.