Chris:
Any estimate of hours of use? It seems to me that the only way to compare life of the sails is in "engine hours," like an airplane or car.
My sails are one year older than yours. We did exactly the same thing in terms of reef points and sail bag storage. I perceive a loss of shape in my jib; you say yours are fine. I reguesstimeated my usage as 120 short voyages over four seasons, with the sails pulling an average of 2 hours per trip, for total sail use of about 240 hours. If you have less use on your sails, then the difference may just be a matter of time. If you have as much or more use, then the difference might be due to use or storage.
By the way, the difference I note is that the jib creases across its foot when close hauled. It used to not do that. Also, my sails have definitely lost their crinkliness. I store my sails rigged under sail covers on the boat at dock all summer. They only live in the roller bags in winter and on road trips. That might have something to do with it.