Slipping clutch

Hello to all, and wishes for a very happy new year. I have just returned from a longish road trip over the holidays (details on the Yeti's snow prowess to follow in a separate post with pictures - I was well impressed!), during which I had a problem with my -recently tuned- Yeti.

It started while on the highway, when I started noticing the revs rising slightly and then dropping when accelerating hard in 5th or 6th gear. I initially thought this was an issue with the new map not holding overboost properly. Turns out that the problem started getting worse and worse, until I realised that it was actually the clutch slipping. The probelm got worse (in retrospect, this was probably due to the constant slipping taking its toll on the clutch and overheating it), reaching the point that whenever I tried accelerating hard in any gear from 3rd upwards the clutch would slip significantly and the car would not accelerate. I need to point out that all of this happened while traveling to northern Greece, and with the temperatures dropping significantly (the problem started at about 3-4 oC, and temperatures dropped as low as -14 oC on several occasions).

As soon as I diagnosed the actual source of the problem I started taking it very easy with the throttle to save the clutch and make sure I got home with no problems. The interesting thing is, though, that on the way back, and as soon as temperatures started rising above 5 oC or so, the problem disappeared. Similar conditions (highway driving, foot down in 5th or 6th) but no slip!

I was wondering whether anyone has any ideas about what is going on. I am certain that the Stage 1 remap had something to do with it, as it seems too coincidental that the problem occured on the first trip I took right after getting the map. On the other hand, I had been driving the car for several days in urban and motorway conditions without any problems before setting off for the road trip. It seems like the combination of increased torque and low temperatures had something to do with it, but I can't be sure.

I will, of course, be talking to the people at Revo to investigate further and hopefully shed some light, but I was wondering whether any of you have any ideas of why the clutch could misbehave at low ambient temperatures. Keep in mind that the car is 2 years old, with about 20k miles on the clock and not any particular abuse having been inflicted on the clutch...