He is probably bored and looking for something to do. I have a several beardies who do that from time to time, it is actually good excersize for them. I take them out and put him in an outdoor screen enclosure I have. Once in there they would immediately calm down and take in the scenery. I think in nature they cruise around alot and explore to find a new place to bask. I would chaulk it up to boredom, nothing to worry about. I bet if you take him out and give him a change in scenery or different enclosure to explore it will help cure the boredom and satisfy his curiousity.