T206 Printer's Mark Question
 

I recently purchased a Hal Chase with an odd printer's mark on the back, near the #350. I thought at first some printing had been erased, but a closer look showed me it was a familiar mark that almost looked like an apostrophe. Wasn't there a thread about this somewhere? This has to be a part of a plate, right?
Merry Christmas,
NJ
http://www.collectorfocus.com/images...hase-blue-port

I am not a printing expert but I think errant marks aren't uncommon. Yes, something on the original printing plate or just an errant piece of ink. :)