Mine is like this as well, nut as long as it stays the way it is it won't bother me. Are you bothered just because the fact that it's loose bothers you, or are you worried about it breaking in the future? If its current conditions is what bothers you, then go check out some display units, either at an Apple store or Best Buy. If all those have the same problem, then that's just likely the way it is.
For me, I'm going to keep my eye on it, and if I see it getting worse over time I'll just get Apple Care. Will probably get it anyway. I figure I'll use this for two years or so, and by then I'll want whatever the shiny new thing is anyway.