I began SR shaving about 1 month ago. I seem to be doing ok with the strop as the razor is plenty sharp. However, when I finish stopping with the leather, there is a small amount of black fuzz on the spine. Am I doing something wrong or is it because of the shape of the razor?

Razor: Dovo Prima Klang (extra hollow ground)
Strop: SRD 3" black latigo with SRD 3" Primium Fabric