I figured out what was going on with my car's brakes. RR caliper was dragging, heating up, and possibly sucking air or boiling fluid locally. Replaced it, bled the system.

Had an oh-^%&# moment as I realized the cap said DOT-4, and I had just poured in DOT-3 (boiling point 450) fluid. From what I understand, those are chemically compatible, so it's unlikely to eat my system from the inside out. Should I just re-bleed all four wheels this weekend and call it a day, or is there a risk of doing damage?