What does this green cheek conure behaviour mean?

[Bobo]

I've had my pineapple GGC for about half a year, and he's almost a year old. We get along well, but he does one strange thing that I still can't understand after searching the internet.

Sometimes when I have him out, he'll move from my shoulder and sit under my chin, then make weird kind of quiet grumpy sounding noises, move his head in strange patterns and rub his beak on whatever he can (sometimes also biting my chin or my shirt), and he flutters his wings a little without actually spreading them out.
I can't even begin to understand what he's doing. Can anyone help?
Thanks!

 

[Dinosrawr]

Sounds like hormonal behaviour... basically your bird is using your chin to stimulate himself to get off. Have your had him DNA sexed? Generally females like to have their back area near their cloaca rubbed, whereas males tend to hump - though females will too.

 

[Bobo]

Sounds like hormonal behaviour... basically your bird is using your chin to stimulate himself to get off. Have your had him DNA sexed? Generally females like to have their back area near their cloaca rubbed, whereas males tend to hump - though females will too.

His previous owner told me he was a male but never mentioned DNA testing. I am a little suspicious but as he (she? they?) are the only bird in the house and babies won't be much of an issue, so I basically opted out of DNA testing until it grows more important. Probably something I should get done now though.
Thanks for the help!