Not sure how this occurs , so was wondering if it is just a worn die. Asking about the area under "In God We Trust" . I did notice the reverse has a crack or lamination issue. I know this isn't exactly an error but was curious about the Obverse. Thanks for your time.
I don't think it's a die issue as it is an issue with the copper/zinc annealing process. These post-1982 Lincolns develop plating blisters in the form of bubbles and lines pretty regularly.