It's hard to tell from the photos, but it's possible that someone simply drew the line on the bill. I'll let others chime in.
Very interesting. Not sure how that could've been made at the BEP but the ink looks to be the same color. I think that's one you have to have in hand to really see what's going on.
I couldn't tell what it is. The edge of a teller's stamp? I don't know what part of the printing process would put that line there. If it goes on top of those features it's probably post printing. Kind of cool looking anyway.
I'll go out on a limb and say that could be excess ink that wasn't wiped off the plate before pressing it against the paper.
I was thinking it was the same ink just not as bold,it could go either way I suppose,idk...The line is absolutely perfect,the BEP ink seems to have more flares than the other tho,I'm divided
Might be a scratch in the printing plate? Those can produce thin straight lines. It doesn't have the look of a teller stamp. Not sure what else to guess....