PARKED IN A GAS STATION PARKING SPOT. I PUT THE TRUCK INTO PARK AND LEFT THE VEHICLE ON FOR THE FAMILY. I TOOK ONE OF MY CHILDREN INTO THE STORE. MY WIFE OPENS HER PASSENGER DOOR AND STEPPED OUT TO PICK UP A LITTLE MESS. WHILE IN PARK THE TRUCK MOVED FORWARD A BIT AND STARTED TO ROLL BACK. SOMEHOW THE TRUCK WAS IN PARK OR SHOWED IT WAS IN PARK (IT DIDNT MOVE WHEN I LET OFF THE BRAKE PRIOR TO GETTING OUT OR AS I GOT OUT OF THE TRUCK). AFTER STRUGGLING FROM OUTSIDE OF THE PASSENGER SIDE AND THE TRUCK ROLLING BACK ABOUT 50 FEET, MY WIFE MANAGED TO GET THE SHIFTER INTO PARK (AGAIN). THE PASSENGER DOOR HIT A CONCRETE POST AND OPENED THE DOOR BEYOND WHAT THE HINGES ALLOW