I had a Ford or a Dodge once that used to have a park pawl that would stick. Starting that car could make it lurch till it got latched to lock things.
I occasionally sit in my car, in park, for a short while. (at the ATM, or in lines somewhere) I have a couple of times had the ICE start, and been startled to feel the car begin to move. It couldn't have moved more than just a minute amount, more like rocking on the wheels, but it sure was enough to startle me at the time!
The car does have a parking brake. It has a regular brake too. Who sits in a parked car without either brake engaged? Oh.....never mind.
P and parking brake when you stop. It ain't brain surgery. If it really went two feet see your dealer, because you have a broken parking pawl in the drivetrain. Even one foot is pushing it. Don't knock people for responding to your post, then edit your post so their comment looks out of line. Really bad manners.
I had the same thing happen to me in my garage. I do think it went forward about 6 inches or so, but when it happens it FEELS like a foot. I think it's just the point at which you put it in park that this occurs. Like I said, it's only happened once, so I assume it's a normal thing every once in awhile.