The date on the paper was 1964, in fact I just smiled and said thanks, but it wasn't until on my way home I remembered that AZO had a rep for staying power.
Ran a quick test with a few sheets expectly fog, but no..... The top sheet and the bottom one had some funky things going on, but the wrapper was moldy so that is no surprise. Middle sheets looked great.

Years ago there was a box of either 8 x 8 or 10 x 10 ( interesting size had not seen before) AZO hanging around the lab and ended up giving it to a student who was doing some contact printing. Never got to see the results;; hope he got good use out of it. It had to be 10 to 15 years old at that time. I was on one of those massive clean up binges. I will be more carefully next time.