Bps prefer to stay in their hide pretty much all the time. That's partly why it's recommended to give them a UTH as a heat source. They do better with belly heat and with the UTH they can get their heat without having to leave their hide. Yours needs to leave the hide to get to his heat source which is why he would be out more often then regular. Plus reptiles are nocturnal which would why he would do it once the lights are out.
Now you also might be lucky and have a bp that just prefers to be out more often. It's not really normal but also not impossible. I would be really interested to see how it would act if a UTH was added to the tank. If it would still prefer the heat emitted from the panel or from the UTH