NPC Spawn Issue: possible aggro bug? Or is this intended?

[Lazortag]

Sorry, this is kind of little, I'll confess that I'm mostly posting this so I can have someone confirm my suspicion here. When I was camping ass/sup to get my friend's mask of deception, every time one of the three mobs would spawn, it would literally always go after her. There was not one time (out of about 30 or so mobs) where the mob that just spawned aggroed me first. We'd guessed that mobs are programmed to attack the lowest level character by default, but I'm wondering if this is known to be classic, or if I'm just misunderstanding how the mechanics work? Is there some other attribute (like distance) that can determine who gets first aggro?