1.8 Windowless Doors Allow Light

When I placed one of the new 1.8 solid doors, the ones without windows (Spruce, Dark oak, Birch), I expected to see no light coming from them. however, they were allowing outside light to come inside. I didn't think that would happen, considering that these doors have no holes in them.

To Reproduce this:
1. Build a 5x5x4 box, wall and ceiling (not floor) included in this
2. Take two blocks off of a wall, at the center
3. Place one of the solid doors (Spruce, Dark oak, Birch) in that hole
4. Stand in side the box during day. You should see light coming through