

Anyway - while checking the exp dates noticed a red Fresh-Check label which I had never seen before.

I checked this site for info on the labels but wasn't able to find anything - so I snooped around and found that the labels are made by a company called Life Lines Technology.
The labels are called TempTime TTI - time temperature indicators. When the center of the bull's eye turns black it's time to toss your MRE's.

see their webpage for more details... navigate to TECHNOLOGY AND QUALITY/HOW TO READ
http://www.lifelinestechnology.com/
(site is all flash - no direct linky)
anyway - i've been lurking the boards for a long time. it's great site.
just never had anything to add.