Hi, I see this intermittently, and it seems to happen when you are zoomed out somewhat and scrolling the map up and down. Sometimes the bottom row of the grid gets visually duplicated several times even though those grid squares are not actually there (see screenshot below; there should only be 1 square of border between the image and the edge of the map, but there are about 5 shown). This has thrown me off a few times when resizing maps, making me think I have more space than I really do. I'm using Chrome on Win8.
