1 year old favoring right arm/shoulder

Hi,
Not sure whether to put this here or in toddler forum, maybe I'll cross post. Anyway, yesterday we noticed my almost 1 year old walking funny with his right arm/shoulder. Almost like he is lifting up the shoulder and not using that arm much. He seems to have no pain, just doesn't want to use it.

I took him to the chiro today who did appear a bit concerned (which concerned me because usually he is pretty laid back about most everything). He did some work on my son who really liked it, tried to go back into the room for more! But no improvement, still holding shoulder like that.

I can't feel anything abnormal, except maybe some tightness, but he looks almost like pictures of kids with torticollis except his head isn't pointing to side.

Anyway, anyone else have experience with this? I really hate to ignore it and find out something is wrong, but since he isn't really having pain, the thought of x-rays, etc. doesn't interest me either.