A tale of two cases... and Capdase case discoloration

I never really place my mobile phones in silicon or other protective cases, but somehow, with the HTC Desire HD's fine aluminum case, it almost seemed mandatory. Within minutes of acquiring my DHD last February, I went into another store and purchased a Capdase Soft Jacket 2 Expose. I loved the way you could still see the phone through the semi-transparent silicon case. 

Fast forward two-and-a-half months later, my fine looking grey silicon case has turn greenish. I am not sure how good it is captured in the picture, but especially under direct sunlight, it looks like, in the words of my friend: "lumot".

 I know that a silicon case is not supposed to last forever, but 2.5 months feels a bit short for the Php900 I paid for the case. I decide to retire the Capdase and get an OtterBox Commuter Case. I hope this one fares better.