Click image to enlarge.

Ok, I've looked at this in PSP 8.  The only area that I can see a problem with is the shoulder.  What was your bucket size during your render? What I see looks about the size of a bucketsize of 64 or 32?

Someone else just had a problem with lines left from the bucket rendering. Unfortunately I can't find the thread where the solution was.  I'll keep looking.

Here is an enlarged image that I darkened the gamma on. You can see the squares.

"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