I usually figure that when they start looking for me they are too hot.

They do occasionally when I've upset them, but they never tell me which hive they are from, so then it gets tricky.
If I stand by the hive and watch and they are headbutting me then somebody is going to lose her head!!

Keep in mind, though, that they are more testy when the weather is bad and they can't get out and forage.
Rick