I never hold the brake after stopping on a really hard stop. I'll shift into park. High temps and holding the brake will definitely transfer pad material to the rotor. My penny.I have no scientific data to back this up but, I think it’s the pad compound that Toyota uses that causes the rotors to “warp” or feel warped from pad deposits onto the rotor. I put organic pads on mine when I replaced the rotors. It stops so much better now. I felt the braking vibrations for the past 10k miles and progressively got worse until I took care of it.