Well, for a phone that seems to be very well built, this issue and the "specks getting under the glass" issue do seem to be defects, but they are engineering defects, as opposed to manufacturing defects. In other words, they should not have made the decision to go with the cheaper electro formed plastic button over the anodized aluminum one, and they should have installed a thin gasket of some kind around the edge of the screen.
But they didn't. So every replacement droid you get will be susceptible to these issues.