I just noticed the monsters have a "deadzone" so to speak where they suddenly appear even though they should have been visible before at that FOV and looking at that angle.
Here's a couple of pictures to illustrate this:
http://i.imgur.com/HAIwg.jpg - no crab here
http://i.imgur.com/B9JJR.jpg - crab appears after turning the player's viewpoint by very little
It's obviously not a big deal at all, but if it can be fixed easily, why not!
