Yes, it is. And under the DMCA, altering copyrighted code is illegal. And you alter the save file every time you save. I guess we're all criminals, then.
The save file isn't copyrighted. It can't be, because it isn't static code.
Incidentally, I'd have thought Shoddy would be on much shakier ground legally, since it reproduces a whole load of copyrighted artwork... That's a separate issue, though.