In my workspace everything looks OK :

If I render it in that size it looks OK as well :

However ... when I resize my cameraview so the head becomes smaller (or just rescale the layer) it renders like this (notice the white edges around the eyes) :

It looks like the masking on the eyes is not working as expected ... strangely enough the issue isn't visible one the bigger versions and I can't figure out why this is happening.
Any clues to fix this are very much appreciated.
Thanks,
-Kim.