The ghost in the Mini

Was just going out in my Wife's car earlier and checked my Mini through the window before leaving. To my alarm, I discovered both the driver and passenger windows fully down. Thank goodness it wasn't raining (for a change) or the car would have been full of water. I didn't have the "key" with me but the car wasn't even locked.

I had to get the key to close the windows and remembering something I saw on a VW Jetta commercial, tried holding down the unlock button and to my surprise, shortly after the doors unlocked, both windows rolled down. "Feature" I assumed but how did it happen when the key was on the dresser?

Ideas anyone?