I've heard many anecdotes regarding dry beans, e.g., if they're too old, they'll cook up tough, chalky, wrinkly, etc....
Although the complexity of carbohydrates, proteins and residual moisture that comprise a legume is overwhelming on a molecular level, the macroscopic physical properties appear simple. A dried bean simply means it's a fresh bean that's been dehydrated to very low moisture levels (for preservation). It's tough for me to fathom anything can really happen to this system over time ("fresh" dried bean vs "old" dried bean). I read a lot of patent literature in food science (FreePatentsOnline.com) and haven't found any information (yet) regarding the implications on the resulting cooked bean if it's dried recently or long ago.
If you're not already asleep, I figured I'd take a break from hunting through the literature and try an experiment.
I had these OLD garbanzo beans in my cupboard. We love our beans in this house and I did not want to loose these. Buoyed by an NPR story on the dried bean, in which the take home lesson is simmer them slowly for a tender bean. Taking that message seriously, I dumped about a pound of dried ceci beans in a 3.5 L sauce pan, filled it with tap water, brought it to a boil and turned them down to the lowest barely sub-simmer heat for 8 hours (overnight). The water was salted. The next morning, after they cooled I tasted a few. Lovely. Perfect bit of resistance to the bite, not chalky, plump, yummy garbanzos.
I'll keep looking for data to support the claim that dried legumes vary in any way depending on how long ago they were dehydrated. I don't expect to find any. But, I'll keep looking (maybe submit this to Mythbusters or something).