The saga of the dead clutch continues

[jalal@lecap.engr.sgi.com (Jalal Rajabali)]

Three days ago I had to tow my 1988 Audi 90 quattro as my clutch pedal
wouldn't spring back.  It was simply dead.  And now after three days
the clutch is working again.  I left the car alone and just tonight
decided to start it up so the battery wouldn't die. 
I have no clue on why a very dead clutch would start working again without
any effort.  Could this still be a Master Cylinder symptom?  
BTW, should I also change the Slave Cylinder alongwith the Master Cylinder
if I do end up fixing the Master Cylinder?

Or should I just leave the clutch alone and hope that it won't die again (yeah right wishful thinking but then again it is Christmas afterall).

Any advice, suggestion, clues very much appreciated.

Merry Christmas,
Jalal