I'm very, VERY new to being a BD mama, but I thought I would respond because my BD did that tonight, while he was on the top of the sofa and kind of excited to be there, after looking out the window. I might be totally off base, but that was the impression I got from his behavior.
My beardie Sorin does that though not to that big of a degree. Why he does it, I don't know. But my vet has cleared him as healthy so it's fine. It's hysterical to watch them run with their tail up in their air though.
Cooper used to run all over the house with his tail curled up like that. From what I gathered he usually did it when he was happy and exploring. I always took it as a good sign like a dog wagging it's tail.
Mine does that too, not as extreme though. But a good portion of his tail points straight up when I let him out of his tank and let him explore and run around.