I've always assumed this was my cat playing - usually if he's annoyed at me he will slink away, or growl. He's doing neither here, and as you can see he alternates between biting and licking, and if I start to scratch him he'll relax into it.
Seeing as I managed to get it on camera, I figured I'd actually ask to make sure, I don't want to be accidentally annoying him rather than bonding.