A strikethrough means this feature would be bridging voids on the die, where the letters are. It's inevitable that 100 tons of force would push it somewhat into those voids. The marks here are perfectly consistent in depth across the lettering, and to my mind could not possibly have been left during the strike because the only way to create that consistency is to apply whatever it is to the letters when they're a positive - on the struck coin. Otherwise we'd have to believe something less than a millimeter wide withstood the force of the strike without bending.
PMD maybe? Something pressed after it left the mint? Look at the lower bust on Lincoln. It looks flattened which could indicate a the coin was pressed. The rims also look like the may have some minor damage at 3 and 9 o'clock. The "punch doesn't line up exactly with the flat areas (which may just be a striking defect). It's a stretch and I'm leaning towards a struck through but something to think about
It looks like what I put on my Christmas leg of lamb, last month, a sprig of rosemary. But that must have been some strong sprig. Does it smell like rosemary?
