I've bought my iPhone 7 September 16th and noticed today a change in color of the antenna stripes - they are getting blueish: 

[![enter image description here](https://i.stack.imgur.com/EAu3N.jpg)](https://i.stack.imgur.com/EAu3N.jpg)

I always wear it in my jeans pocket without any case or sleeve. 
Is there something I can do to clean the stripes?