It is called de-lamination or as I like to call it "fingernailing." It is caused by the CA being the first thing the fitting comes in contact with when pressing it in. Take a razor knife with a new blade and trim the excess CA from the end down to the wood. Or you can use double-sided tape to stick a piece of 400 grit sandpaper (with a hole big enough to slide over the mandrel) to the mandrel base and turn it on slow. Then, just ease your blank up the mandrel and gently touch it against the sandpaper until the excess CA is removed back to flush. This will cause a little ridge to form on the end, but it is no problem to take blank off the mandrel and touch up the edges on the same sandpaper while it is still turning. Then finish and polish.