So Mango is making the same sorts of sounds and maybe I am just continuing to be more observant or notice more subtle things.
Lately he seems to be ducking his head more and saying Uh Huh while looking at me with one eye. He doesn't always duck his head when doing that though, and sometimes he does it while eating with his head in his food bowl. Sometimes we start a back and forth Uh Huh exchange.
Now I started wondering if that is an aggression kind of things, and my giving it back is irritating him.
Now, if I put my hand in his cage to have him step up, he will either walk away, kind of reluctantly step up, drop his head and put his beak in the way, or slightly spread his wings and fully lunge. I can always tell how it's going to go before we'd meet. Sometimes I can be just as stubborn so I've figured out a tight fist will prevent him from being able to bite. He's seemed to stop trying, actually other than the lunging, which I'll back away from and leave him alone, he has not bitten me in a long while - I've forgotten the last time.
I think it's just my own perception, but I also feel like he wants to interact with me less (more beak in the way and walk away). I don't bother him much if he's like that.
I read from the Google chronicles that drooping head is a breeding behavior.
Seems like longer than 6 months since I've had him, but that's all it's been.