Haven't seen it mentioned here yet, so my experience...
had a similar issue, brakes dragging and overheating, but only at track days. rebuilt calipers, new pads, hoses.. brake ducting.. finally discovered the problem when i went to replace the master. The pivot bushing on the brake pedal itself was sticking just enough to keep residual pressure on the master. spent a lot of money on a problem that could be fixed with a spray of lube
