I had same problem Saturday evening. Parked on a hill facing downhill, handbrake frmly on in neutral. Left the car for about 6 hours and when we came out of the house the car was 15 meters down the road ! When I went to get in the car, still a litle confused as to how this had happened, it lurched forward. I pulled the handbrake tighter and it stopped. I suspect that being a very cold night, there had been some shrinkage in the disk just enough to let the car lurch forward now and again but not enough to completley release it. If the Ford ASO team are reading this, and I suspect they are, better monitor it carefully guys ! Remember big brother is watching you (TREAD).