It appears at some point it was plated as far as the weight there is a +/_.13 so it appears to be normal.JMO (with damage) Dave
It can be overweight (+) or underweight (-) by as much as 0.13 gram and still be within mint specifications.
Looks like Environmental Damage to me.. That Cent was affected by the elements and corroded a bit. I have seen dozens like yours Metal Detecting. Not a Mint Error.