I am leaning towards it being an error rather than PMD but welcome your expert thoughts and opinions. Lincoln's face has some sad scratches.
I think its possible that the out of round part may have been out of collar. It looks like a "struck through a blank/unstruck planchet.
I am hiking Mt. Katahdin tomorrow, but I will put a picture of the rim on soon. You can see where it was partially struck (I believe) out of collar. The rim on the one side has a lip.
See below Sal. Place another cent on top of the coin. I believe it will fill that curved area 100%. To balance the top coin you can place another cent next to the area in question. This is the only example that I available to me at the present time. See how the lower cent fills the upper cent incomplete space. I think you will see the same thing happen on yours.
I note that the bulge in the rim aligns with the raised ridge in the voided metal, In God We is weakly struck in the void (or seems to be), and there is an odd double rim on both sides. It does appear to exactly match the diameter of a cent.