09 Clubman S, new to me, rear door light
 

OK, so I just bought an 09 Clubman S, yesterday. When I was looking at the vehicle, the rear door light was fine. Or I never noticed it. Then, as I was driving home, I noticed that the rear door lights kept flashing, as if the doors were open. But they were not. I opened and closed the doors a million times, no help. I drove 200 miles to buy this vehicle, I'm not inclined to drive back to ask them to look at it if there is a simple solution.

Suggestions anyone? Or any other info you need from me?