This happened to me yesterday for the first time. Went out to inspect at about 1:30 pm. Hive #2 was very active at the entrance. After I removed the lid and started to inspect they boiled out from the top and bottom, flying in circles, landing and crawling on me and everything else. This was unusual (but very cool) for me so I decided to close them up and move to hive #1, which had non of this behavior.
I returned 30-60 minutes later to inspect hive #2 and all was calm.
Another unusual behavior I noticed was that the bees were pooping on me and my camera when they landed. I havent seen that, to that extent, in my "normal" inspections. I guess that would also support that these were orientation flights of new bees.