I think what you may be referring to is the slight color mis-registration surrounding the denomination that looks a bit off-center and thus gives an odd appearance. It is not an error, but merely a color mis-registration that is generally referred to as a "freak" and thus has no philatelic value above that of a normal appearance stamp. In fact, many collectors would prefer a "perfect" example of the stamp rather than a "freak".
As a comparison, I pulled these two sets of five used stamps off of
ebay sales to demonstrate that the color mis-registration around the denomination is quite common on this series of stamps:

Note in the first row shown above, the fourth stamp is so affected, but not the others.
In the second row, the second and third stamps show similar color mis-registration -- one shifted to the right and the other to the left. In fact, even the fifth stamp shows a slight misregistration, too.
It merely demonstrates that these color shifts were quite common to the issue but does not command any premium value because of it.