[JayG]

A couple of things.

I disagree a little with Husker.

It's really hard to actually warp the rotors. Most likely, you have pad deposits on the rotors.
That being said, if the rotors have a fair number of miles, replace them. You can also possibly have your rotors turned to clean and smooth . The min thickness is on the edge of the rotor.
Rotors arent that expensive, so turning may not be worth it anyway

I highly recommend Meyle drilled rotors. I used them for several years of tracking and never had any issues with cracking around the holes

What pads are you using?

It is a good idea to cool your brakes after a session. If you can't get a cool down lap, drive around the pits and/or access roads for a couple of minutes, trying not to use your brakes. You should not be going very fast in the pits anyway

YMMV