Loose screw on 5D Mkii

Yesterday I noticed that one of those tiny screws above the lens mount is loose, it sticks out a few milimeters but I can't move it with my fingers. The camera was stored in my Lowepro backpack with 70-200 on and I have no clue how this could have happened.
Should I just tighten it, or does this warrant a call to Canon?
(I think tightening it and then watching out if it happens again is good enough for now, but I wanted to hear other opinions)

Okay I'm admittedly a very impatient person so when nobody replied I just tried to screw it back in. Surprisingly the screw is in there tight, now I'm even more confused since I know it was flush in there before..

It's a loose screw, no need to send it on a two week journey just to have a tech give it a turn or two. Break out a small Philips and tighten it.

Thanks! I tried, but its tight so I didnt want to force it (odd) so oh well, I really don't want to send it out for something like this, I was mostly just concerned how this could have happened.

If it is too tight to turn, my guess is that something inside the camera that it is supposed to screw into has shifted enough that the holes are no longer in alignment.

A cardinal rule that only the foolhardy ignore: If something is stuck, don't use brute force to move it unless you are thoroughly knowledgeable about what you are doing.

These are tiny delicate parts and the camera is quite expensive. It might cost you to have Canon service the existing problem, but it is a pretty good guess that it will cost much more to fix if you break something else.

Also, if something has shifted, it is reasonable to assume that the camera might need to go through an alignment/calibration procedure.

Since you're in the Atlanta area, maybe you could call or go by KEH or Camera Repair Japan and just see what they think.