I would exchange. I don’t think that’s the intended effect. The metal on my Tortoiseshell version is covered nicely by the acetate.
My turtoiseshell is completely covered as well. Seems smooth transitionaly around the edges.
I saw several reviews both ways. There’s a review from Digital Trends that is exactly like mine.
Same for engadget:
https://www.engadget.com/2018/09/13/master-and-dynamic-mw07-review-true-wireless-earbuds/#