When listening to the radio (NAV model), the shading around the selected preset has dark shadows corresponding to the text displayed above the preset (see pic). It appears to be only where the text has a vertical line. In the attached pic, you'll see the shadow directly below the vertical line that makes up the T, both verticals of the H and the vertical of the E. This is faint during the day but more noticeable during night lighting. Is this normal?