We had a lightweight 2 piston front kit on a car a little over half as heavy as yours and we would discolor the rotors, especially after a visit to a short track where you really had to use them.

Regular inspection for cracks or heat damage, both on the rotors and pads, and paying attention to signs of warping and pulsation is a good idea. Discoloration by itself is mostly normal. Like anything else, repair or replace used up parts.