It kinda looks like a lamination, based on the fuzzy area on the bottom half. But the curved line looks too sharp for that. A late stage off center strike by a late stage capped die? I don't know. Wait for the experts.
I did a bit of research on the error a few months back and it looks a lot like this and the coins on this thread, so I was pretty sure that that's what it was.
Nice find and a cool error. It still would be nice to see the reverse side of the coin. I would get that into an airtite. So that it doesn't get any staple damage.
Back looks normal. It’s actually out of the flip now and I’ve got it in my ‘modern dime’ slot in my type set. It’s a great conversation starter.