How do you know they were nurse bees?
I shook them off a frame of brood, in the middle of the day when the temps were in the low 60's. Since the foragers were flying around, I just assumed the ones on the brood frame were nurse bees.
I'd say you are right. How much brood did they have? I'm in TN too, but I haven't opened my hives yet and I'm wondering how much brood I might have by now.
I thought that it was generally safe to move nurse bees from one hive to another - at least safe as far as fighting and killing the queen goes.
Maybe they just didn't care for the Hawaiian queen. Was she a Carniolan?