I'm experimenting with a procedure to graft a male-morphed V4 head onto an M4 body.  I've finally ironed out all the kinks except this one.  I call it "bruising": shadowy areas along the head/neck border that look like deep creases even though the mesh is perfectly smooth (trust me, I've looked at it from many different angles in "Hidden Line" view).  The morphing brush seems to help very little no matter what its settings. 

In most renders, it's not a big deal since this particular part of the body is likely to be hidden by hair.  Still, it's bugging me, so I was wondering if anyone has had a similar problem and might have a few suggestions.

Thanks in advance!