I'm not sure if these marks are "氧化" or not. Luckily, I just got 4 AMCDs only (Lam 85 still factory sealed) because I'm not happy with the sound quality - totally out of balance and "EQ-sound". That's all.
I've never noticed such marks on other discs, even some of them are 20+ years 銀圈 from my collection. I don't think it's because of 溫度/濕度. Let's see what will happen with your AMCD......
Actually, I cannot find any information (to the moment) for this "4N Pure Silver, Made in USA, Limited/Numbered, etc" disc - just on the cd's booklet alone.
Anyway, I will not buy these high-tech AMCD anymore. Waste of money. Goodbye AMCD!