Attempting to recreate a confirm this, I think I see what you are seeing. In the color panel, if I place the hue slider in the maximum position (top right) with the area at one end of the ribbon then move it to the opposite end of the ribbon you get a difference of 0° to 350°. Interesting find. @jefftranberry will probably need to confirm this one.
In the highlighted yellow boxes below you can see the gap remaining in the ribbon in the bottom example of the two screenshots.