Now, perhaps it's because I don't restrict myself to Hour of Twilight dungeons. This is because I don't need the gear from heroics, and so I might as well get to see dungeons I haven't gotten to see for a while. Now, if the confusion was just happening when I was DPSing, I'd be less baffled. I mean, if you're tanking your way through normal heroics to try and get geared enough for HoT dungeons and eventually the Raid Finder, sure, I could see being somewhat nervous of the dude in 410 gear who just dropped in. Really, I could get that.
What possible reason do people have to freak out when a tank in 410 gear shows up? Do you honestly think I'm running Lost City of the Tol'vir to take your gear? Is that actually happening?