What is going on?

The other day I cleaned out the trays below the screened bottoms.  There were a lot of bees on the tray of #3.  This was curious but I did not think about it much.  Today I saw a lot of bees Fthe front of the hive, like bearding, but it did not seem hot enough for  that (it was in mid-60s).

Front of the hive

Backside

The tray was pretty much covered with bees before I brushed it

I started walking closer to get a look and, while still over 10 feet away, a bee stung me on the side of  the nose!  (I tried to get a picture for your amusement, but the swelling did not show on the selfie.)
I wanted to know what was going on, and figuring that there might be something odd happening inside, I suited up and went in.
There was some nectar in the super that I put on a week ago.  (One week ago I took out the Apivar strips and put supers on all the hives.  I also added four bars to Olea's.)  The were 3 frames of capped drone in the top box.  In the bottom box, there was capped brood and larvae of all ages, including very young.  I did not see eggs nor the queen.  There was one empty queen cup, no swarm of supercedure cells.
So, everything looked fine inside the hive.  I guess they were just bearding, but I have no explanation for the increased aggressiveness.  I did take the entrance reducer out in to increase ventilation.  As I type this it has clouded over and cooled a bit and I can see that they are all back inside.