I've looked (closely) at thousands of bills in my long life and NEVER have I seen a serial number 'out of clock'. It must be rare (at least).
No, nothing really special about it. I recommend looking at this site though. http://coolserialnumbers.com/FancySerialNumbers.aspx
my wife looked at me and said: 'where did that (phrase) come from? Somewhere long ago and far away, since now I'm 77.
If you search this forum for "turned digit" you will find several examples. They come up every few months it seems. https://www.cointalk.com/threads/serial-number-question.242323/#post-1860790 https://www.cointalk.com/threads/series-1969-1-star-note-star-is-off-center.240945/#post-1845019 https://www.cointalk.com/threads/displaced-digit-in-serial-number.199296/#post-1357071