It is normal Robert. Look at this way, The hive is strong and at night all the worker bees have taken a break from foraging and are at home with all the rest of the girls.
it is a warm night and with all the extra body heat in the hive it is getting too hot for the comfort of the queen and brood. It is about now a break in the cooler fresh air is sounding pretty good and i have heard through the grape vine there is a slight breeze blowing as well. I’ll just go out and hang out there in the beard…