US 2013 1-dollar bill with extra number

Silentinsnow

I recently found this 1 dollar bill. Close inspection, I found it has a red number 9 on top of the lower serial numbers. It looks like one of the fibers from the process of making the bill. Have anyone found something like this before?

JDsCoins

I have not, It does look to me like a fiber that forms a perfect 9!

Great eyes haha

Steve_in_Tampa

A little curly-Q

synchr

That is a silk thread that curled in a peculiar way.
Great find, keen eye and exactly why these are used as security features