chromatic aberration and green screen ghosting
 

Has anyone noticed what seems like some sort of pixel shifting going on when filming a subject in front of a green screen. It appears as a dark line on the left side of the subject and a lighter line on the right. It is only visible on solid surfaces and more noticeable on darker colors. It shows up more vividly in HD but somewhat in SD. This shows up on the original footage before the keying is applied. The keying software seems to see this as part of the subject and leaves it in. This has nothing to do with bad lighting or spill from the green screen. I am wondering if this could be caused by chromatic aberration. These lines are not so big that they cannot be removed using clean up controls but to produce a perfect key I do not like doing this. These lines should not be there to begin with. I would appreciate any input on this.
Thanks Mike