With certain print applications, the plates are rubber, which are glued to a backing, then placed around a print cylinder. With use, if the print run goes at a faster speed, and the backing comes unglued, there gets a bubble of print ink that gets rubbed up against the material being printed. Quality control might miss a few of these misprints. It may run on as few as 5 or ten when the machines are sped up , then settle back into it's proper spot for a while, then come unglued more later, when it's noticed by the operator of the printing press. Usually when it's noticed, the operator looks back at the latest product and determines how much of the product is scrap, and destroys it, or sends it on with a note telling the next operator what portions of the product is no good if some is still usable. For productions sake, they don't spend forever looking back through a product though, so some misprints invariably get through. It may be as many as a few thousand, or as few as five. Now, I guess it's up to the individual traders to determine if it's worth more due to the misprint, or less. Either way, it was a good find.
