It's as rick said, a grease filled die. Grease drops on to the die and other debris like dust and dirt also can be accumulated and prevent the proper strike to be completed.
I've seen my fair share of these with all the roll searching I do. So yes, quite common but not sure if it has anything to do with location, but more the great amount I look through. I mostly do cents and nickels by the box full but not the other denominations. I think this is what you are asking.
