Alert showing up when selecting weapon I am already using

When playing on Song Be (I doubt the map matters), I had my MG out and decided to take a quick look at my inventory using my mouse wheel (which does not automatically switch). After taking stock of my inventory, I mouse-wheeled up to my MG (which I was already using) and a blank alert/hint window on the right side of the screen popped up and didn't seem to want to go away on its own. You can see the alert here:
http://ift.tt/2sEma0n

When I selected 1 (or switched to another weapon using the number keys) the alert went away. I tried this several times to make sure I could reproduce it (and that it wasn't just a fluke) and it happened every time.

I just brought up a new game and went into free play and could reproduce it every time, though it does go away after a while on its own. If I use my sights or switch to any weapon (including the current one) it closes the window. This appears to happen on any weapon or item in my inventory.

Alert showing up when selecting weapon I am already using