I noticed the darker red backs also. The yellow glowing on the front is most noticeable in the logo in the 40. The 91 Topps are crazy when it comes to the ink. The regular card in the picture is strange also, not only does the yellow glow on the front but so does the red along with most of the front of the card. But the back does not glow.
I collect the strange and weird.
Just wish it was a Wade Boggs error instead of Nolan Ryan.