The post-1982 cents are made from copper-plated zinc planchets. These suffer from all sorts of ills and anomalies. I think this is the well-known plating bubble. I'm not surprised at anything I see on the Crappy Zincolns. See what others have to say.
I agree with @Kentucky. Information re plating blisters can be found on the following site: http://www.error-ref.com/?s=plating+blisters Below is an example: (Not my coin).