I mounted a dragon at the Windhelm docks and when we took off we flew over a frost troll so I told the dragon to attack. Apparently, there were some hunters down there as well and after killing the troll the dragon attacked and killed at least one, and perhaps more of the hunters. (It was at night and snowing so I had trouble seeing what was going on.) Despite this, I did not pick up any bounty. So my question is: if you tell your dragon to attack a non-hostile NPC and the dragon kills it, do you pick up a bounty?

Also, interesting comment I heard from one of the hunters: "I'm not sticking around to fight a dragon!"