I only know of two people thus far with a paint issue on the Stealth out of hundreds so far. Jpmilner and kenman345 were both early adopters of that finish. Jpmilner uses them every day for long periods of time. We have not got them back yet to even know what came off and why and kenman345 had a one of the first sets that was experimental in nature. He has the latest finish now and I don't think he has had any issues with it. The frosted clear shells are now coated with a UV protectant which should diminish the effects of yellowing in the sun. I would not ever leave any IEM in the sun anyway.
Is that what caused them to get that tint of yellow? I always thought it was oil residue from the skin or even sweat residue :p