Yeah, I've got a bit of play in all three, and enough in the sleep/wake button to cause a small rattle. (There's also a tiny rattle separate from that, which other people theorize is in the camera.) This seems pretty common, and a poster on a previous thread about this said they looked at like 15 floor models in an Apple store and all had some kind of play in the sleep/wake button. So I probably wouldn't worry about it.