Update on this:
I have a 2017 model with the same issue. The marks are apparent underneath BOTH speakers.
I've gone back and forth on it, but I decided I'm just gonna live with it. It's only noticeable in certain lighting conditions and I can't 'feel' any difference when running my fingers across it. However, it is disappointing that there's a 16 page thread on the internet about this issue, which is prevalent in the 2016 models, and Apple hasn't remedied this for the 2017 models. It must be part of a step in the anodization process as others have alluded to.
I have a 2017 model with the same issue. The marks are apparent underneath BOTH speakers.
I've gone back and forth on it, but I decided I'm just gonna live with it. It's only noticeable in certain lighting conditions and I can't 'feel' any difference when running my fingers across it. However, it is disappointing that there's a 16 page thread on the internet about this issue, which is prevalent in the 2016 models, and Apple hasn't remedied this for the 2017 models. It must be part of a step in the anodization process as others have alluded to.