You opened a brand new never opened up Wii U? If so what your describing may be the plastic they put on electronic devices to help protect them.
Heres a picture of what I'm talking about.
found a thread on neogaf which stated its from humidity and that it can be dried out. So I put it up to my heater on high setting and its starting to dissapear.
So anyone else with this issue put a blow dryer or heater next to it and it should resolve your problem. Just from humidity.
- Crackkat likes this