Is it normal to get cracks in the rotors often? Car is a 2nd Gen with Mazdacomp ducts, Hawk blues. I put new rotors on 3-4 weekends ago (Brembo front, house brand rear) with 2 weekend old Hawk blues. I just noticed there are lots of small surface cracks on both front rotors, rear rotors are fine. Calipers are new and bled every other weekend.

What causes this - overheating? I was going to replace the front rotors but was curious why this happens. Also, I should run my Hawk blues down to the line in the center of the pad, correct? I've seen people lightly file down the pad surface when changing rotors, yea or nay? Thanks!