car running in park shifted to drive and drove into garage

I backed out of my garage and completely outside of the garage. The garage was slightly up hill. I put the car in park and got out to go in the house for my sunglasses. I walked completely through my garage up two steps and through my laundry room. Then I heard a crash. When I went back to the garage my car had moved from the drive way into my garage and crashed into my garage wall by my steps. I know the it was in park when I got out because i walked around the car from drivers side and through my garage. If I had left it in gear it would have hit me before I got through the garage. This is a lease and I took it back to the dealer and they said it was intermittent they couldn't reproduce it. I am leaving on vacation in two days on a road trip vacation. I do not trust the car now. Has anyone else experienced this?