Thanks, I see it's an actual alert (which, if you have the option turned on) would result in a push notification as well. I can't check myself until I'm back on my personal machines (at the office today) but can you make sure you aren't "watching" that category in the Media/Gallery section?
If you see "unwatch" click it and that'll stop your account from watching the category. It's possible you watched the category a long time ago but because the Media/Gallery section is barely used, combined with the newer style of Alerts & push notifications in XF2, then seeing alerts from that section is now distracting.
If you see "watch" then I really need to poke around to see what's generating those alerts for some of you guys.