Yes, it looks like there is ally wearing. Two things suggest themselves, either the steel washer behind the prop driver is rubbing on the crankcase nose, (it shouldn't while the engine is running as the prop should pull the shaft forward) or the prop driver is rubbing on the cowling, the photo shows that the cowl is pretty close to the prop driver, the muck is coming from the front, and you can't tell if anything touches until the thing is flying, and it can be hard to see. There will be witness marks on the driver or the washer if there is any rubbing.
Evan, WB #12.