If you make a new canvas and set it's roughness value to 0% you get horizontal striped shades of white. They are very faint, but they are there. If I tilt my flat-panel upward I can see them better.
Mac OS X - 10.4.10 - Intel
I exported a blank canvas and did an Auto-Levels in Photoshop to exaggerate them for easy visibility. Attached below.