Vibrating Clutch

[TooManyAudis at aol.com]

I just got bock home to Charleston, SC from a trip to Orlando in my 91  200q. 
 No problems on the drive until....  I got back into the drivers  seat after 
letting a friend drive for 250 miles or so.
 
There was noticeable vibration in the clutch as I pulled back onto the  road. 
 I didn't get the vibration each time I depressed the clutch, but  about 60% 
or so.  Sometimes just when I was releasing the clutch after  changing gears, 
other times both on the down stroke and again on the up stroke,  and a few 
times no vibration at all. 
 
Note, that this was not happening before my friend took the wheel -- I  don't 
think he was the cause, just coincidence as he has owned a Porsche 911, a  
Scirocco and several other manual tranny cars in the past.  I simply am  
deflecting blame from myself.
 
Any thoughts?
 
-- Tom
 
Isle of Palms, SC
91 200q
88 80q