[Superman]

I once replaced a clutch in a Nissan Pathfinder (not an easy job) unnecessarily. It was slipping because there was not enough freeplay in the clutch pedal. There was some, and it seemed like enough, but it was not enough. When cold, the clutch did not slip. but apparently heat expanded the fluid and, since the MC pistons were not able to retract fully, the pressure built up in the fluid system and cause the clutch to slip. Apparently, pressure is released in the system when the MC pistons retract fully, allowing fluid in the system to bleed back into the MC reservoir.