There's always a plate number in the upper margin of the sheet. The error is that the back of your note is so far off center that the plate number ended up on the note instead of being trimmed off with the sheet selvage.
That's a cool note. It's a miscut, see the first listing at http://papermoneyguide.com/currency_errors.html
That margin is nice and wide. I think there's extra value for this note because of the printed numbers up there. Too bad about the ink on the front, which is centered correctly. So is it still a miscut? Because if the reverse was cut correctly, the obverse would be off. But the obverse is centered.