After parking on a slope, front of car uphill, slope of about 15-20 degrees, placing car in park, the car would roll back once out of car. It happened once and went up against another car, minor scrape, but I was almost pinned. I moved the car to a different spot with similar slope, it happed again. The wheels were rotating, had to jump in passenger side and push hand onto brake. It had happened once before, but went up against a curb, but I had thought I had parked poorly. But in retrospect, likely rolled. Tried to call/contact VW, but it is a Friday and they do not accept safety calls Friday evening through Tuesday.