My beardie has been known to do that sometimes too, usually in the morning after I turn on the lights. I figure he's just "flexing" -- you know, making sure all the equipment still works, just in case he needs to either intimidate someone or impress the ladies with the "big bad macho dragon" routine 8)
I do sometimes wish that I had telempathic superpowers so that I could get inside his little reptile mind for just a few moments and find out what he's thinking, feeling, etc :?