I believe bp's are actually crepuscular being active during twilight (dawn and dusk) not nocturnal. So yeah it's a little weird that your bp is active during the day but not weird that he sleeps at night. They would sleep day and night being awake during the short hours that are neither, twilight.

Make sure your husbandry is right, and that he's eating correctly. If it's all good then you've just got a bp with a strange sleep pattern, they've all got their own personalities.