could be a bad clutch plate ,it DOES happen....in 1972 I bought a NEW Volvo a 142 manual, one of the few new cars I bought...I traded in my old Volvo 122 with 110k on it...in 1600 miles the clutch went out...they claimed it was "driver who didnt know how to shift"...at my dads dealership!

I told them to go look at my trade, also a stick shift...it was still there...check the mileage...I had driven it for 3 yrs...they did put a new in under warranty , I drove that car to 85k....no more clutch problems