Die trail error on 2018 cent? It's VERY minor, but I can see four lines above, which would make sense. There is only one line below (off the F) that cannot be seen in this image. I noticed that the JF is thinner than normal, so that also lines up with this being die trails. Thoughts? I realize it is super minor, but since there is a site dedicated to cataloging these, I figure it might be important enough to list. Edit: I also think there are planchet striations present here, but they are all tiny compared to what is around the initials.
I'm not an expert on these but IMHO they appear to be a continuation of the lines (striations) that were on the planchet before the coin was struck. Here's a photo of Die Trails as shown on error-ref.com: Wait for the experts!
Looks like it could be die polish. That would also explain your observation of thinner letters. There are also radial flow lines toward the rim which indicates a die that's bad some use.
I think it is very unique. The striations on "In God We Trust" make it appear 3D. My opinion, it's a keeper. Thanks for sharing.