Brick-based blocks appear grey in maps.

Lately I decided to start building using brick blocks, so I made a town with various houses. One of the houses has a brick and stone roof, but when I made a map of my town to see how cool it looked from above, I discovered that the bricks don't show up red on the map. Bricks appear as stone on maps, a dark grey color instead of red. This can be easily confirmed in creative mode, just pull a map and some brick blocks out of the creative inventory, lay some bricks down, and look at the map.