So I’ve seen a lot of folks online scratching their heads about “how can carbon expire?” or “my carbon fiber (bike/boat/etc.) is N-years old, is it expired?” but I think the most likely thing to expire is the resin.
Well it would have an expiry if purchased from Boeing. All materials used in aircraft have stringent performance requirements. Resin is a plastic and like all plastics it degrades over time. It can lose strength and fail to meet materials ratings. Now if you wanted to make something like a regular boat hull out of the stuff it would probably last a lifetime, but if you want to make something like an airplane wing, that's a different story.
Anyway carbon fiber composite is stronger and lighter than steel, but the wonderful thing about metals is they can have good properties for supporting all kinds of loads. But even then you have to inspect for fatigue on a regular basis when loads cycle repeatedly. Carbon fiber doesn't do as well with that.