when you go outside and run around does it meant hat you don't like your parents? nope...it just means that you want to get out and have some and burn some energy! You would be amazed how many characteristics, both physical and mental, that animals have with us humans.
Its funny how ten people can see the same thing and yet you can get ten different answers on what your seeing
My opinion is that your seeing a dragons running on instinct. What I mean is, if you put an animal in a room where he is not accustomed to the surroundings, I feel you'll see him searching for areas to fulfil its needs. I feel that the animal isn't running around happy, but is searching for heat, security, food, humidity, whatever. Beardies, by design, don't burn energy aimlessly. A dragon accustomed to an area or accustomed to being removed from their enclosure, will behave differently.
I'm not too sure what emotions dragons feel. I'm not too sure some of the emotions they feel can be described by our definition of the word.