1992 Voyages Of Columbus --Error Or Not?

I purchased another set of the 1992 Christopher Columbus souvenir sheet pack this weekend at face value. In closely examining each sheet, I found that the stamps on the "Claiming a New World" (5 of 6) sheet are offset to upper west corner, and the $4 stamp has a offset print of light yellow mark on the lower right of the stamp image (boundary where the well-centered image is supposed to be). Is this a common error? not an error? or just a bad centered example of modern issue?

Any comments and advices are greatly appreciated!