There are times when I'm scared of the bees.
Two of my hives contain very large colonies and, this season, they've been unhappy when I've looked inside. They've also been unhappy when I've watched from over 2 metres away - a bee will investigate and then attack. This is new behaviour from my home hive and fear is a new feeling for me.
The defensive behaviour of Hive A might be due to the time of year but I suspect that they've replaced their Queen. Her temperament should be the same as before but she may have mated with a drone with a more defensive temperament.