Thanks for the suggestion. I did call them prior to posting here and they asked me if the tires had been driven on. When I said yes, they transferred me to their warranty department. From there, they couldn't really help me. Yes, they would accept the tires back under the Michelin 60-day satisfaction guarantee, but in order to return them, you have to replace with another set of tires (from any brand). They essentially credit you the cost of the tires to apply to another set. No chance of monetary refund was my understanding.
Unfortunately, that's not what I would want as I've decided to return to my original tires that I kept and they still have plenty of life left. So I have no need for another new set of tires at this time. I suppose I could exchange them for tires I would need in the future and just store them, but they might be a few years old by then, which is not ideal either.