Posted By:
DaveWI like the hair theory, it would explain why it doesn't show up more. I checked, and the ink streak goes from just above the scroll at the top to the bottom of the card, a little over 2.5 inches, for what that's worth.
I'll take a look at my other Piedmont 150's, but I don't remember seeing this before.
Edited to add:
I've checked all my cards, which has 108 Piedmont 150's. The card I posted is the only one with the streak.