See the two images below - If I'm at a reasonable zoom, the bees resource looks fine, but if I zoom in enough, the shadows at the bottom get covered up by the land.
This happens with other tiles too if they have something near the bottom...
http://dl.dropbox.com/u/8683962/beesbefore.png
http://dl.dropbox.com/u/8683962/beesafter.png
