Hello and that mark you have... this the the Achilles heal of the Cambium... its the standard failure point. Its the start of the saddle failure and will be replace when it fails, just not until it fails.
Its not cosmetic per say.. but at this stage, you cant tell if it will progress into a full failure. Think of this as a "crack in the lacquer - just cosmetic" of a carbon frame... in a point where loads of the same frame have failed! You know its going to go like the others... or not... just when is the question.
When the cambium first came out this was a real issue and they were sending out new top covers all the time, also new "rivets" too, as they were falling out. Brooks got "wise" to this and now only replace when a failure occurs, not before.
If you use google just look at all the images and yours (just like my one - mind only 1 out of the 4 cambiums I have) is failing.
It seems that there is both fabric reinforcement and a metal plate inserted into the molded nose of the saddle. If the bonding between the metal plate and the rubber is bad or goes bad for some reason this will help the saddle fail. Because there is a large change in stiffness at the rear of the metal in the nose, the saddle flexes more across a line at the rear of the nose metalwork; this can cause loss of the cover fabric on the outside of the saddle and may cause splitting on the underside.
