Parakeet Bobs His Head While He Makes Coughing/Clearing Throat Noises

I've recently caught my parakeet making noises which sounds like he is clearing his throat or coughing but at the same time he is bobbing his head. I've only seen him do this twice so far and its usually when I'm around him.

I think he is regurgitating but do parakeets make noises when they regurgitate? I've never seen him do this before so I'm not sure if this is something I should be concerned about. He'll make the noise a couple of times while he bobs his head and he'll even do it if he's on my shoulder. Anyone have any idea what he is doing or what it means?