it hasn't rendered enough passes to see for sure.. but I believe the issue may be in the specular color.. was fooling around in studio and used the uber hair(silky) shader on the hair, which changed the specular from the default light grey specular to full black specular.  with the change in the specular, it hasn't shown up yet.. but it's still only 20 passes or so in but i'm not seeing them.  usually at this stage you can see a slighty halo around the hair.