You can read all the books in the world about beekeeping, and while you can get a good idea of the fundamentals, nothing beats experience on how bees behave.
Take the photo below. I have no idea what the girls are doing. My best guess is they are fanning the hive entrance for temperature control, but they could just as well be practicing their Cirque de Soleil routine. Nothing else seems amiss, so right now I just have to assume everything is fine, and this is some normal bee behavior I haven’t experienced yet.
If anyone has any ideas, I would certainly welcome any feedback.
Urban Beekeeping in Austin, Texas 
I have the same thing happening on one of the hives. They seem to move back and forth for some reason, but other hives are quite, sometimes I feel that they all left the hive, but I open it, lots of activity going on there.. Any expert opinion would be appreciated.
Might be time to remove that entrance reducer.
Maybe they are washboarding?
http://myrmecos.net/2010/08/19/washboarding-bees/