I don't seem to have this problem when I drive but today the wife had the rear hatch open while she was stopped at a light. Then as she was coming in to park next to me at a restraunt it opened again. She said that it has happened speraticaly for the last couple of days but today has been the worst. I'm going to go for a little spin to see if it happens to me . I'll post later what happens.It's a 07 mcs we got just before christmas.

 

There was a thread about this not too long ago. I think the cause was water getting inside the switch. If it's under warranty, I'd take it in. Otherwise I think the fix was to remove the handle and seal up the switch/wiring connectors at the hatch.