Flyspecking A C91

Found these two stamps rather interesting (taken from the corner of two different plate blocks).

Probably very common for this stamp, but it would seem that the vertical centering of the words "USAirmail 31c" on each stamp, along with the black bleeding into the blue-colored lettering at the top left of the stamp makes for an interesting comparison. I know they are not significant enough to warrant any special mention in a catalog, but it does make for an interesting study:

There are all kinds of things going on comparing the two stamps. Not the least of which is the upward slant to the bottom inscription on the right stamp. Some major shifts.

Wow good eye wt1 I didn't notice that right off until I read the dialog...It would seem that it was just a misalignment or mis-registration and as you well know that is rather rampant on that type of printing process. it is offset? right?

I don't think there is an upward slant in the bottom inscription. It appears to be parallel with the inscription at top. I think it is an optical illusion caused by the fact that the entire stamp is tilted in the picture.