I have noticed a minor fault/depression on the dial of my Rolex black dial Submariner (the new Submariner "ceramic" version) ..... the centre of the dial has a 5-6mm diameter round depression/dip from the hole where the hands protrude through the dial. Its not easy to see with the naked eye, you need to catch the light in just the right way and then the dip from the reflection of the light is visible. Does your Sub have the same issue ? .... I'd be very surprised if this is particular to just my Sub, I suspect its just a feature of the manufacturing technique although I must admit that I would have expected better given the overall quality of the dial in general.