My colony is thriving and the bees are gentle. However, if I go to the hive to just look and observe without disturbing anything, it seems there is always one guard bee that attacks me. She will bounce off my head repeatedly even when I walk away. I have to get at least 50 feet away for the single bee to stop. This has been going on long enough that it isn't the same bee the whole time but it is always just one. Is this a common behavior? Maybe the color of my clothes (my t-shirts are usually dark). My wife just got chased in as I'm typing. She is wearing dark shorts and a royal blue shirt. Any suggestions?