I'm surprised that it took this long, especially since I've opened the hive to look twice without smoke, and the other openings with smoke I've had them crawling all over my arms and hands without incident. The worst part, I wasn't doing anything with them. I was on that side of the house, and they like to fly around and investigate, which I don't mind.
From the best I can figure, the little one landed on my hat, got caught in my hair, and gave me a good pop to the back of the head. Of course, the wife, being allergic, freaked. I went over to the garage and grabbed a sting swab from my med kit in the ATV. I love those swabs. But alas, it gave me a reason to get a haircut. Now it's at 1" long, so hopefully that will keep them from a repeat incident.