If you're battery cover is loose I say take it back. Apple's quality control seems to stink as I have had issues with three macbooks having warped lids, never had the battery cover problem, but it's the same idea. No, it doesn't effect the functionality of the product but for this kind of money it should be built well. Have you ever seen a windows based pc from any company have consistently bent lids and loose battery covers? I'm sure some do but it's not as widespread as this issue with apple. And not returning it b/c other wise its a great product just lets apple get away with selling products that are poor quality. Why fix it if people buy it? take it back an get a new one. Such a physical imperfection on a machine this expensive is hardly acceptable in my opinion.