Yes,you are right. Usually when it happens people know the reason they were rounded up. That was not the case in this scenario. Actually the dream seemed pretty pleasant up to that point. Something about my name being called just changed everything,for some reason. And the signature thing is something I dreamed about one other time. In that first instance,it was not a mailman telling me to sign but some older gray-haired man in a gray suit and fedora. I got confused about where to sign because what he handed me looked like nothing but a piece of newspaper. And when I asked him,he just snapped at me to "sign with my accent",whatever that meant.