I figured I would do a follow-up since more than a few people stopped by for a look.
After an avian vet visit his best guess since there were no obvious dislocations, and no noticable limping on the legs was that in certain positions the Keel bone interacts with the leg/hip motion, thus making the "popping" sound.
I noticed it mostly when he would climb up my shirt or on an angle. The doc (Dr Loudis in Encinitas, Ca) broke out the parrot skeletal diagrams and showed me the possible interraction areas.
So, after getting his nails trimmed and attitude subsequently adjusted, Hahnzel is back to being the awesome, yet friendlier version of the guy I know him to be.
