I showed it to the vet today and she said that there was nothing to worry about!!!
She looked at it for a while and felt it and said there didn’t seems to be anything under the skin, but that he just has a spot of different pigment on his skin. She said that normally, it occurs under the lighter fur, but it was under his black fur and there didn’t seem to be anything wrong with it. The fact that hair was growing through it and not falling off of it was also very good. She said just to keep an eye on it, but that she was sure it was just a phenomenon on Bing that his pigment was in such an unorthodox place! It makes him even more unique!
I plan to keep an eye on it and have already measured it with pictures the best I can, but I think everything will be be okay after all.
And, I got him insurance last week, so I’m just excited that he is protected and ready for a long and happy life. 
Otti, I’ve had him since June 2010. He was born on 4/1/10.