It's at 500 post. Obviously, you are WAYYYYYY over that. A PP mentioned that her avatar was messing with her "status". That could be the case in your situation, too.
It didn't switch because of your tags. But if you try to fix it yourself it will delete your tag fairy tags. If you want your status changed post on the Tech Support board at the bottom of the main page and a Tech Support Mod should be able to help.