I bought a steak at Safeway 5 weeks ago and kept it in the refrigerator. I took it out for dinner yesterday and it was all green and fuzzy. Should I return it for a refund?
That might sound sarcastic and I DON'T mean it that way. Kudos to you for asking. Here's another example:
I bought a bag of flour at Safeway 5 weeks ago and put it in the panty. I was about to make pancakes this morning and it had a rancid smell to it. Should I return it for a refund?
You expect flour to last many months. If it doesn't last like all the other flour you've ever bought, you are right to wonder why and to ask for a refund. Maybe they didn't rotate their stock and it was a year old when you got. Maybe there was a manufacturing or blending issue and it wasn't any good the day you bought it.
But a reasonable person doesn't expect raw meat to last for a month. That said, a clueless person (a vegetarian?), through lack of experience, might be surprised.
I know things about the aging of fabrics in 2014 that I didn't know in 1976. Because I've now owned and used cotton, nylon, polypro, polyester, leather, and their various coatings for many decades. I'm still using uncoated nylon gear from 35 years ago (Yeah!, Patagonia Baggie shorts!) But all my urethane-coated nylon fabrics from 20, 25, 30, or 35 years ago is delaminating. So I've learned that there is a lifetime to that material. In a few cases, I recoat it myself. Other times I repurpose to a non-waterproof use. Or I toss it or use it as un-coated fabric for MYOG projects.
Yes, you're probably within your rights to return it, by the letter of their policy at the time you purchased it.
I don't see it as REI's fault that they couldn't predict the lifespan of fabrics that had only existed for 5-10 years at the time.
I wouldn't return it myself.
If we want manufacturers to use the most modern fabrics when they've had no chance to field test them for decades, perhaps we have to accept an unknown useful life and roll those dice as we see fit.