Forming that area (because it is the deepest in the die) is a constant event that creates that area on the coin. It can tend to crack there. Often seen on quarters. The eventually weakens the die and it cracks on that area. Kind of like trying to bend a cracker:

I remembered this cartoon through the years. Didn't remember when it happened and thought it was Charlie Brown, but it was Linus. 1956. That was many years/months/weeks/days ago. I found it on the internet.