I'm inclined to think "misuse" of the chemicals, rather than age related matters. If there isn't a "Use by" date on the boxes, the concentrates are stable. And even if there was a date, you can be sure it's very, very conservative, even to the point of not at all. Does Rollei or Tetenal or (liquid) Unicolor put "Use by" dates on their packaging? Kodak, et. al., would definitely spend a goodly amount of research and money to prevent disaster.
Originally Posted by Terry Christian
That you left Starter out would fall into my hypothetical category of "misuse." W/o looking at the MSDS and knowing what chemicals are in it, I'm going to make a guess and say that it functions somewhat in the spirit of keeping a bit of old B&W developer in the next batch.