The "chatter marks" you see are not from the knife lines, but the dotted lines in the transferred pattern. You'll notice in photos later in the sequence that the knife cuts are smooth and continuous, and the dotted lines have been buried in the tooling.
As for what is causing them on your carving, one of the more common causes is choppy movement of the knife through the leather, especially when going around curves. If your knife is not sliding very smoothly through the leather - seems to "pop" a lot - it can be an issue of either a poorly sharpened/stropped knife blade, or the leather could be too wet. If you can post a photo of yours, we can probably get a better idea what's going on.
Kate