This is the response I got from Smith and Wesson Customer Service. BTW I did send them a photo and am waiting for another response.
Good morning,
Thanks so much for reaching out and for choosing the Model 19 Carry Comp Moss Limited Edition, we're glad to hear it's performing flawlessly for you.
Regarding the wear you're seeing on the cylinder: what you're describing does sound typical, especially with the Cerakote finish. Cerakote is designed for durability, but it can show signs of wear a bit differently than traditional bluing. The marks behind the circle rings are often just a result of normal use, especially after a few hundred rounds.
If you'd like to send a photo, we'd be happy to take a closer look and confirm everything looks as expected.
Let us know if you have any other questions.
Best regards,
Rebecca