Looks like a shallow strike through. I can't see any detail in that area, but the lack of any displaced metal rules out damage for me.
Here's a detail of a deep strike through that I have in my collection. Do you see any fine lines or pattern on your coin?

ANA ID: 3203813 - CONECA ID: N-5637 Clean a coin that may be worth collecting? Please DON'T! When in doubt, leave it dirty!!
