I got my 2013 Air a few days ago and noticed sometimes a mosaic block showing up on top of certain bookmark bar in Safari. If I move the cursor on top of the mosaic, it disappears and the bookmark turns normal. The location of the mosaic are different between the occurrences. It has happened a few times and I had taken screenshots of them. I wonder if I got a bad unit and there may be incompatibility between Safari and the new video card. Any ideas?