Steering Wheel Button Wear

I have a 2015 C250 Bluetec. I was wondering if anyone has come across any issues with the buttons wearing on the steering wheel. My RH volume button cluster has worn with the rubber peeling off, yet it's isolated to those three ranked buttons. The rubber coating feels different with these three buttons too. It's really strange.
Is this a 'thing'? or is it peculiar to my car?


