[Paperboy]

Have experienced the following 4 times now during a 12 months period.
The gear change suddenly goes slightly notchy, like the clutch is not engaging properly or all syncromesh are worn. Has happened both on start up and during drive with every thing warm.
If the car is parked and restarted later a very smooth shift is back w/o any action taken.
Have pressure bled clutch, checked pedal mechanism and carpet not intefering.
Neither cluch cylinder has been changed during my 14 year ownership. No visable leaks.Clutch fluid pretty clear when bled.
Any ideas? Clutch ? Gear box? Gear linkage.