Check the 4 hinge bolts, maybe they're loose? The door can be moved by slackening the hinge bolts and shifting the door (out/in or up/down, but out/in travel is minimal). However if the door has been moved the door lock/latch has to be adjusted on the B pillar (the bottom bolt has to be slackened after which it can be moved around, but if the latch on the door doesn't catch into it properly or if it rubs into it then it has to adjusted by removing or placing spacers underneath the lock/latch). If the gap isn't that visible and the door closes properly then might be best to leave it as it is. Is the door rubber seal in good condition?