cdnum,
That difference is caused by a misalignment of the black color on the stamp -- you'll notice the "USA22" also also appears higher in relation to the bottom of the image on the right-hand stamp.
It is not uncommon to see such misregistrations. Here is an example of a color shift on an earlier US stamp.
The U.S. Stamp Society's Glossary of Terms puts such color shifts in the "Freak" category.
Quote:
*Freak - a mistake in production caused by an unusual circumstance not likely to be identically repeated, such as a color shift, perforation shift, inking irregularity or paper fold. A freak is a less severe and less valuable mistake than an error.
Steve
Posted 12/30/2010 07:57 am
