I can't speak to these particular elastomers, but elastomers as a class are very stable and maintain both dimension and spring rate over time unless abused badly.
The thing they don't like is heat, but I doubt you'll ever be using them beyond the design temp. If you're concerned, let the bike cool back down after transporting in a car trunk on hot sunny days.
Or if you're wondering what may happen 5-10 years from now, but a spare and toss it into the back of your fridge.
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