You say under the chrome? What chrome? Is there a molding? If it lines up every where except along the bottom, then the door probably needs to be moved in on the hinge. If it is all the way in on the hinges then a few other things come to mind. Do you live in an area that is prone to rust. One, is that someone might have installed a rocker panel up past the hinge mount area and the hinge is simply out to far off the cab. Two, maybey someone did some patch work on the bottom edge of the door and now it is built out.