It is a submissive behavior & males who feel threatened by a female (usually a larger female) or another male,, will indeed arm wave. As the others stated, it is a communication & if there aren't any other beardies to "talk" to, then why would they do it?
As far as the gaping, what are the cage temps? Basking "surface" temps? It can take some time for them to cool down, especially if the temps are too high. That all depends on what "room" temps you are talking about too. If he is gaping in his cage at 110 and you take him out in a room that is 85, it will take some time. Now, if the room is 70, he will cool off much quicker.
Hydration plays a big roll in thermo regulating too.
Also,, they sometimes take a gasp for air when they are shedding & their "nose plugs" are still in. (the shed within their nostrils) The first time I saw this, I was freaking out. I thought she had a respiratory infection for sure.
I hope this helps.
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Joel R
Coming some day.
www.SpikesAndScales.com