Error variations vs. Print Variations: 1990 Fleer Martinez

[deweyinthehall]

In my quest to assemble master sets, I've decided to pursue genuine errors (e.g. the '89 Ripken) and not go after what seem to be mere printing variations (e.g. the '90 NNOF Thomas).

I'd like to ask people what they make of the 1990 Fleer Dave Martinez with the yellow "'90" at the top.

I initially considered this an error - it was set up, in error/absentmindedly, to be printed in yellow and was later corrected. But the more I think about it the more I wonder - I double checked and found that ALL cards in the '90 Fleer set have the "'90" in red (I had assumed that cards with Yellow fronts (like Seattle, etc.) featured a yellow "'90", but it's always red no matter what team it is.

So, given that no cards were meant to be produced with a yellow "'90", which could have explained an accidental yellow variation for Martinez, I now wonder whether it's more likely that something happened with some of the original sheets that took a red "'90" and produced a yellow one instead.

I don't know a lot about the printing process, but I think red is achieved by combining yellow and magenta - could this variation have been produced by a failure for the magenta to come through? If that is the case, though wouldn't there likely be more variations like this for cards from the same sheet?

Thanks for whatever insights people might want to offer