Sometimes when I open or close the tailgate, the right hand side pops out of the socket (probably because I'm pulling up on the handle). If I don't support the (pretty heavy) tailgate, the corner drops onto the bumper and I now have a slight dent in the sheet metal of the tailgate. Is this normal? Shouldn't there be some sort of locking mechanism to prevent the corner popping out? Of course, this is my first pickup so maybe I just don't know how to open and close the tailgate properly.