It sounds like the light triggered orientation flights which is normal. Covering it helps them maintain proper brood rearing temperature. If it is in a window getting direct sunlight, then you would need to cover it to keep it from becoming a giant wax melter and to keep them from flying during cold weather in winter. If it is not getting direct sun and the bees are able to raise brood, then you don't need to cover it all the time. But, I keep mine covered because it doesn't hurt to cover them when no one is looking at them and makes things easier for them.