Since I have AA off, there has to be some sort of internal AA that isn't able to be turned off. Otherwise there would be jaggies galore.
It's probably a newer version of Alan Wake Engine:
http://community.remedygames.com/forum/games/alan-wake/alan-wake-help-issues/6830-alan-wake-pc-graphics-settings said:Antialiasing can't be disabled in Alan Wake, as the engine has been designed so that AA is on at all times. If you disable it from e.g. driver's control panel, the game will likely work but you will see visual artifacts.