Those belts are pretty hard so if it's marking it you need to find out why - maybe a rock is wedged in the cover or some such

Found it. small rock 'glued' itself to the 'valley' between teeth of drive sprocket, probably from fresh asphalt - lots of road works around here. I don't know if that would be covered under warranty. Hopefully didn't damage it too seriously.

But now, I'm a little bit disappointed. Belt was supposed to be reliable and maintenance free solution. I did pre and post drive inspections, so I know that it took just one ride (45 minutes) to do the damage. It took me some time and sweat to remove sprocket cover, and to inspect and clean every teeth on both sprockets and the whole belt.

This thing can happen anytime. So, how reliable are these really? Or, it's just a bad luck on my part.

I've been told, the lower belt cover is real important for keeping rocks out of the belt.   Althopuh I noticed that it's the first belt cover many people remove.    But..............

About two months ago, I picked up a stone from a fresh "tar & chip"  job they did down the street.   It was about 1-2 hours old (yuk!!!).   Luckily it was a slow speed spot, just after an intersection that I turned from.   I picked up a stone in the rear sprocket.   And maybe because I have the belt set for the "90 deg" tightness, the bike really shook.  Or maybe I should say "Thumped" with each wheel turn.....    I was 500 feet away from my house.......  made it home .... thump.... thump ... thump.....  thought I blew up the tranny because I had slammed on the brakes and down shiftewd real hard to stop the bike....   it was a relief to find out that it was only a stone.  I inspected the belt... no dents but I could see a mark / discolored spot where the stone "thumped" the belt.....