Mikey, you may have some nectar in the honeycomb and the bees are using air flow to cure it into honey. Looks normal to me too.
You mentioned slatted racks...They are optional in my view, not necessary. The thing about slatted racks is that my queens like to hide down there. Sometimes that is a problem. But, I do use them when I'm setting up a hive with a Cloak board to raise queens.
Here is the paper given to us about the Cloak board when Sue Cobey talked about queen rearing at Texas A & M University a couple years ago.
You want a lot of bees in the hive to start and finish queen cells in the same hive. The slatted rack allows more bees without the crowding that can cause swarms. Its use might help on super hot days too and we have a lot of them here. Other than using slatted racks for queen rearing, I don't use them. JMO