Shower facuet question

I have a new 180 with a separate shower.  I've had it out on five trips so far and love it.  I've noticed that the shower facuet assembly has some play in it and the caulking has come loose on the top of the assembly. It's possible it was always loose but the caulking kept it from being visible.  My question is, is it supposed to have some play (maybe this helps keep it safe while trailing over bumps etc.), or should it be tightened? There is no obvious easy to way to tighten it based on what I can see.  I'm getting ready for another trip and don't have time to take it in right now.  I do use the shower (and love it).  Hope this makes sense.

THANKS!  I bet that's it.  There is a metal rectangle that this screwed to the wall behind it.  I wondered why that was there.  I will check on this when I get home.