"gratitude reflex" seems like a good name for it. Makes me feel like it's out of my control, like jerking away from a source of pain, or laughing when tickled. And that's certainly how it feels. One can now construct a plausible just so story that wanting to find a target for gratitude or anger is one impetus for supernatural beliefs.

I wonder if there is any evopsych and/or neurophysiological basis for this feeling being a reflex.