That is a Machine damage issue. The mint mark is a bit higher than the devices, so during the ejection process they can get damage a bit. So if you see nothing else affected, that is probably what happened. I noticed on your coin the leaf above the mint mark looks like it suffered something at the same time. If other area are affected, then it might just be a die movement during the strike issue. (MD covers all events that happen during the strike, like die movements or ejection doubling. maybe others I can't recall at this time. so it is called MD because the damage to the coin happen during the strike/after)