I have a 2003 Boxster with the 5 speed. If I hold the clutch pedal in while stopped for more than about 10-15 seconds, as in waiting for traffic to clear before making a turn, the pedal springs back about halfway and then slowly returns to normal. If I hold it in for a traffic light, it will only spring back if I tuck my toe under it and lift. Transmission shifts normally in all driving circumstances. The clutch itself was replaced about 10,000 miles ago.
I'm guessing a pinhole leak in the hydraulic system, but there's no evidence of fluid on the car or ground. I will take this in for service, as I'm not a DIY guy on cars, but I want to have an understanding of the system so I can make sure the shop does not just throw parts at me.
Any insight would be welcome.