I'm assuming most of us have experienced the restless leg feeling at one time or another. That antsy feeling you get in your legs which forces you to just move them in whatever way is convenient to get rid of it.
I experienced something similar at work yesterday. Wanting to draw, I was, of course, not able to and suddenly I felt the same kind of sensation in my arms, and chest. I had to kind of shake my arms a little to make it go away.
I've decided to call it, Restless Drawing Hand Syndrome. Or Restless Artist Syndrome since it wasn't just my hand.