Internal Apple memo says that "edge stripes" are appearing on some Apple Watch series 3 units14
According to an internal memo sent out by Apple to Genius Bars and Apple Authorized Service Providers, a problem is causing "edge stripes" to appear on the face of certain Apple Watch series 3 models. These "edge stripes" appear on the non-cellular version of the smartwatch. The cellular models might have been spared because they use a different display assembly than the affected watches.
Anyone bringing an Apple Watch series 3 model to the Genius Bars and Apple Authorized Service Providers complaining about the "edge stripes," will be asked to rub the display with their finger. If this smearing of the display doesn't reveal the "edge stripes," the display will be cleaned and the customer will be asked to breathe on it in order to create humidity on the glass. This would seem to indicate that the stripes appear due to moisture trapped under the display, although Apple's memo doesn't reveal the reason for their appearance.
Since the Apple Watch series 3 is a relatively new release, the original one-year warranty is still in effect. This means that owners should not have to pay for the repair.