I'd go with ignoring it as well, but I can definitely see why it's wigging you out--it either is supposed to be set with an invisible attribute, so it gives pause when that suddenly changes for no apparent reason. Sure, its being visible doesn't hurt, but the question is why.
Did you, out of curiosity, install anything before you noticed this? Perhaps some 3rd party program, or run a disk utility of some sort? That might explain it.
Two things you might try if you haven't already: repairing permissions might include the visibility bit, which would fix it. That, and run whateer disk utilities you do have to see if they report anything amiss with the drive that might indicate a more significant problem. Just to be paranoid.