CA AND PA or CAPA are two methods of continual improvement.
There is no need to think of a PA after a CA for a noticed non conformance, in your case the cosmetic problem via the
8D to customer. You should rather work on how effective your CA has been in further eliminating such a defect. So revising document and any other sure steps that you take are the CA after finding the root cause of the problem
This learning can be such, that when you have an other cosmetic inspection requirement, you apply this and before hand prevent such cosmetic problem from surfacing. When you are so aware that you are applying the learning of an earlier corrective action, you are doing a preventive action and how effective this is for this new situation will again depend upon its effectiveness monitoring.
In both the cases you are continualy improving.
Logic: Once you have a problem and detect the root cause of it and take actions to eliminate it (CA) you will perform so smartly that the same problem due to that cause will not recur again in the future (PA)