The Calm Before the Swarm?

Or is it just the bees out enjoying a rare (for this season) time outdoors?  I'm thinking (hoping) the latter.  I have really never witnessed a swarm, so don't really know what to expect.  If this were animated, you'd witness a steady march of bees up the hive to the cluster near the top.  This was late afternoon, and many bees were in the air, but much pollen was being brought in and there also appeared to be a number of bees just seemingly taking orienteering flights.  At least they were just circling around in front of the hive, as well as I could track them with so many bees about.  We walked out back later, after supper, and the number was considerably smaller and I sure didn't detect a swarm anywhere nearby, so my guess is they were all just out enjoying the pleasant afternoon and are gradually making their way back into the hive as the evening coolness descends.  The other hive was also very active, with a smaller group clustered on the front, but not like this one.  I've seen some big bearding in the summer months, but never this early.
With this hive, you notice there are four boxes, with a queen excluder.  I did put a honey super on 3 weeks ago, and when I checked last week there had been a little comb drawn out but not a significant amount.  I think there is enough room in the hive, though this queen seems pretty vigorous.  Maple, ash and birch are producing pollen at present, and the dandelion bloom is in full stride.  There may be an early honey flow if the promised warmth of the coming week holds up.
I also added a super to hive #1, though the new frames I had put in the top box were only about half way full. With so much in bloom right now, I want to stay ahead of the game.

With so many bees in the air coming and going in this part of our property, you do have to kind of keep an eye out, since they seem to be everywhere.  Note a few dandelions that have not been mowed under, and the large pasture with horses in the background.  There are woods both to the left and right of this photo as well.