Mine did the same thing, but it was only masking the deep underlying problem. It slipped pretty badly at first, in the colder weather, but when it got warmer, it stopped. No idea why, and Jamie at Alfa Workshop down here couldn't explain it either. But, clutch slip of any kind isn't good, so I got him to change the clutch for me and basically, I ended up having to change the DMF as well as frankly.....it was completely shot to pieces. Not sure that it being nearly gone had anything to do with it not slipping, but changing both the clutch and flywheel has made a MASSIVE difference to how the car drives. Its smoother, it changes gear much more smoothly and lightly and frankly, I think I could have done some serious damage to the gearbox and driveshafts if I had left it for much longer. I can only report on my own experience, but intermittent slipping is exactly what happened to me and although I caught it in time and its been absolutely worth it, it cost me £1200 effectively......not a cheap problem. Might be worth getting it checked regardless before it becomes expensive or damaging.....fingers crossed for you mate!