I've never noticed anything like that on my renders.

Can you post a screen capture of your render settings window?

Also, are you getting this with all renders, or just with that one image? If it's just that one image, it might be something peculiar about that skin texture.  Are there material room shaders involved?

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi