Firing pin damaged?

I just swapped my uspc to a lem and I noticed that part of the firing pin that the hammer strikes is not a full circle. Is that normal and I have just missed it all these years or did the pin break on that end? I dont have access to a camera now but to describe you have a full circle and cut a straight line through it removing 1/4 on the right side. The cut is vertical from 12 to 6. Did I miss somthing or did it break?