Yes, I had a stuck clutch with an Alfa Romeo Spyder I used to own. Just sitting one winter did it. And of course leaving drum brakes on (via the emergency or parking brake) for extended periods can seize them up too. But once broken free they tend to work OK.
Pilot bushing is a bronze one, and was replaced when I first built the engine, 6000 miles ago. I didn't do much of an inspection when I had it aprt 1500 miles ago, but I did "look" at it and it appeared OK.
On the re-adjustment, I have had luck with changing the clutch fork play (when clutch is engaged...pedal up) for some things (noises), but they are usually repetitious in nature. This problem does go away.
Last time I checked the clutch, I did notice some transfer of disc material on the flywheel. More of a stain than anything. And because of the pattern, I could tell it was from sitting a while. I just cleaned it off with Scotch-Brite and some Brake Klean. I contaced McLeod about the colour of the disc, which had darkened a bit since I originally installed it, and they told me that was normal.
Keeping in mind I've only a little over 6000 miles on this car over the last 12 years or so (and no it's not a garage queen... just driving it isn't as much fun as building it) I suppose the clutch disc could have absorbed moisture and with the extra dampness and cold these days, it just grabs for a while until it warms up. Next time I have it apart, I think I"ll change the clutch disc and clean up the pressure plate and flywheel just to eliminate that possibility.
EDIT: I forgot to add, I think all bolts are tight, but I'll check them to be sure. Good idea, that. Also, I do have some suspicion about the left front motor mount, so I think I'll check it out as well. This clutch grabbing is kind of like a clunk, but drive-shaft, u-joints and differential are all good. Transmission mount is new.