Possible supercharger issue

[tmthree]

Mercedes C230 Kompressor (2002) - whenever I give the car some gas at the beginning and end of a gear shift, where I’m on and off the throttle, I hear a slight grinding sound. Only at the beginning or end of throttle engagment (even a slight rev in nuetral, not touching clutch pedal). Has been occuring for a few months with no noticeable performance change. Doesn’t seem like a “healthy” noise for a complicated engine.