I had pushed the stock brakes to the max. I was going very fast and braking hard. They froze up and then the pedal went to the floor later. I think it was just the fluid boiling. The next day all was fine except for a slight vibration from the warped rotors (and incredibly dirty rims). I rebuilt my calipers but they really looked fine (to my surprise). I think if you just replace the fluid, pads, and rotors you'll be ok. But you might as well get better lines and rebuild the calipers to be safe.
