Weird funny behavior

[veimar]

My lovely first GCC is about 5-6 mo old and very well tempered. He can be moody sometimes, but overall he is very sweet. Recently he started doing this funny thing - he usually sits on the top perch, and as soon as I approach the cage he would go towards we to the end of the perch, throw himself on his back grabbing the cage with one leg and chewing the nails on another! LOL When I start teasing him a bit trying to stroke his belly or back from outside the cage he makes his funny "annoyed" chirps and tries to bite me, but doesn't go away and keeps chewing his leg! He can do this forever! If he accidentally falls off (he makes these totally impossible moves!) he climbs up right away and goes on. He does that all the time and I'm having a lot of fun playing with him like that, but I wonder if it is excitement or aggression. How to make the difference? I also try to teach him to lay in my palm belly up, which he is a little wary of. (he loves to hide and cuddle inside my palm(s) otherwise while sitting on the perch or on me.)
Do you have any ideas why would he do such weird thing?
He also stretches his wing and leg on one side and often raises his wings opening up his tail like he is exercising. He sometimes wags his tail too. Is that normal? He gets a lot of attention and out of cage time (I actually never close his cage when I'm at home), so I think he moves enough.
He looks like a happy little bird, but just wanna make sure everything is okay. I never had a bird before.

 

[Dinosrawr]

Welcome to the forum and congrats on your GCC

Many of the questions you have asked have been previously answered in the past, so for more thorough threads I would use the search function. But I will give you a short and sweet response

- Annoying chirps and following movements: cage territoriality. Completely normal. Excitement is not very painful for you, but over excitement often leads to aggression that can result in nasty bites.
- Wing stretching: could you imagine sitting all day and not stretching your back, arms, or legs? That's what's happening. They're not flying all the time, so they feel the need to stretch to relieve muscle tension. Totally normal.
- Tail shaking: Often after being pleased with something or pissed off... can determine by feather ruffling. Totally normal.

A simple Google search will bring you to oh her websites with lots of other behaviours and their common meanings. Everything is quite dandy with your little baby