I have a 1986 D penny and on the reverse, it seems as if the letters E, S, and O in "United States of America" were not stamped correctly to where they lay completely flat and are almost non-existent. I have no idea if this is just wear or some type of error.
IMHO, it doesn't look like struck through grease. It just looks like the letters were hit the wrong way causing the letters to smash down lower to the surface creating and effect that may LOOK like the coin was struck through grease. -Brian