To me, it doesn't look like someone purposely messed with it. I would say it came that way from the mint, but I cannot specify the mechanism of error.
Maybe - the die broke during the strike, the broken piece of the die partially fused to the mint mark - upon ejection the broken piece of the die caused the mint mark to rotate and then broke off like a piece of slag. Then again the big gash to the right of the (7) in the date might be the key to answering the question.
Post-mint damage. I was thinking it might be a basement job, but that doesn't make cents. There's no error I know of that looks like that that someone might be trying to fake.
I've made a few phone calls, finally got in touch with John Sinnock's people and they are very interested in the coin.
It wouldn't be a bubble under the plating...it's a clad coin....no plating involved. It could have been struck by a damaged die but I can't be certain from the image.