Raustyk occasionally does something similar. You see she is a big time groomer to Nanook, the cats & I. she loves to lick you from head to toe, especially the other dogs/cats ears & my feet. Sometimes she gets carried overboard, she'll really get into it and sometimes when that happens she starts to hump the air and she's usually in a kind of squatted or fetal position. Sometimes she even does it when she's grooming herself (but it need not be in the privates) I'd say it probably happens about once every 2-3 months. I think it's just a dominance issue. But when it happens when she licks herself I don't know why that happens. Would she try to dominate herself?
She's my girl but not all there upstairs. lol