No, I have never seen those before, but you reminded me of something that happened to me a few years ago when my ex-boyfriend and I were camping. I went to shampoo my hair, and on my way back to the tent, I noticed that there were three or four bees swarming around my head. I started running back to the tent, and my boyfriend started batting them away from my head and quickly shoved me into the tent and zipped it shut. He said that it must have been the shampoo...I had washed my hair with apple-scented shampoo. I don't know if that's what it was, but I was terrified!
Looking back, though, it's kind of funny...I must have looked pretty funny running through the campsite with all these bees swarming around my head!