Is there something we should do about this?

My 3 1/2 year old is deadly afraid of anyone and anything that is dressed up in anyway. I mean spongebob, mickey mouse, pirates, train conductors. He will start crying mad, running away, screaming, sweatomg, and you can literally see terror in his eyes. With everything around these days and everywhere you go there is always someone dressed up esecially in kids places. If he sees one of these dressed up people he wants to go home and its hard to convince him otherwise. Its a real fear for him, and I am wondering if it might be a phobia instead of just a fear that he will get over. What do you think and what should I do ?