Sticky clutch disk

[fnmag58]

Need some help on this one. I have a situation where if my car sits for more than a day, the clutch disk sticks to the flywheel. When you depress the clutch pedal and bumping the key, you're not quite sure what to expect--I've learned to make sure there's nothing behind it. The cure has always been to put the tranny in 3rd and bump the key one more time--this frees it every time. The clutch disk, pressure plate, TO bearing, and pilot bearing are all new. The flywheel has been reground. No rust, etc when i put it together and i did lightly grease the tranny input shaft before assembly. Due to radiator problems, i have only driven the car about 20 mile this year but now that I've got that fixed, this has shown up. Once it's free, no problems the rest of the day, no grinding during shifts. Any ideas? Car is a 1982 S3 with the Xflow with the 4 spd sport box tranny. Thanks.