When I read what you wrote it makes me think of the bobbing around they do when they are all tensed up and ready for a strike. Its like their heads are bobbing to their heartbeat or something.
Then during the swallowing I have some snakes that almost look like a metronome when they are constricting their muscles around to actually manuever the rat down their throats.
Video like mentioned would help alot. If it is wobbles though there is nothing the vet can really do for you. If its eating and acting normal the rest of the time I wouldn't dwell on it too much.