If your bag seems fine it is fine
I am not an expert like Docride but in my experience, if you are happy with the bag as it is, don't mess with it too much. With my black Togo B, I run a Lexol wipe over it every couple days to get off "natural" pollution and dust especially if I am in LA, Dubai, Beijing, etc. I gently wipe the backs of lighter bags at the end of most days because of color transfer, but over-cleaning can be bad as well.
Sorry for OT
but I think pre-spa care is somewhat appropriate?