This is a very easy fix... Since it is new, I would go back to either the AD or the RSC just down the road. All they need to do is place a bit of loctite onto the screw thread and put the screw back in, this will do the trick
You cal also do this yourself very easilly but since it is new I would just have them do it.
The AD may not have used loctite when they sized the bracelet for you, a mistake in my book but again should not be an issue
Lets see some pics of your new watch