Do you $20 bills have pink stains

For some reason, the vast majority of $20 bills I come across always have pink stains on the edges.
I've never seen this on any other denomination, just $20s.
What gives?

 

Log in or Sign up to hide this ad.

Banks machine's marking their bills

 

Thanks

 

I’ve seen a pinkish/reddish tint, but I see more of the black variety.

The story I hear the most is, whoever loads the ATM’s, marks the edges with a wide felt tip marker every 100 notes to help calculate the totals with just a quick glance.......not sure how valid this is.