Tpu case discoloring?

I have tpu case for its compact fit. I was happy with it mostly, but I started to notice the case turned yellowish instead of its opaque color. Is it normal or Is it a case of just have a cheap case from bay?

SchneiderMan said:

First of all why is your username "Applehater"?

Yes some TPU cases discolor like my Belkin Grip Vue..

Click to expand...

I thought only cheap ones do. I was being sarcastic with my username.