See here: http://imgur.com/a/YgTRb
The non-apex sandbag walls have a LOD texture that is a different color than the closeup texture. The close texture is white-ish tan, the far-off texture is a more brown-ish tan. This causes the bags to look very strange when integrated into sandbag bunkers, which don't have this LOD issue.
This isn't a rendering issue; the actual textures are pretty clearly different colors, as shown in the imgur album.