A few weeks ago I got my iPhone 4 replaced by Apple because of a fault. The replacement now seems to have a loose back panel. If I try to slide it sideways it will move a bit. None of the other people I know with an iPhone 4 have encountered this and I'm not sure if I should be bothered taking it back to the store or just keeping it.
Should the loose panel be cause for concern, or is it nothing to worry about?