but I do have a notice that I don't want my art distributed without permission, because I'd rather like traffic to come to my site than some random Tumblr or other site.

Wow, yes. I don't have a note in that vein but I always assumed that that goes without saying. Is that not basic netiquette? Not to mention copyright issues... reposting something in its entirety is entirely different than riffing off it by creating derivative art, or linking by posting a preview thumb at the most. (And personally I would even ask permission for posting a thumb, I guess, out of politeness.)

If they post the artwork wholly they're redirecting our viewership to their sites. Not cool. So I really hope that's not the norm.