Tattoo "staining"?

Has anyone heard of a tatt ending up with a light 'staining' around the design??? I have other art and never had this problem before, but 6 1/2 weeks ago I got a (approx) 4" X 4" tribal black tiger on the inside of my elbow area where the arm bends. I followed the after-care instructions to the letter. I showed it to the artist and he advised that it was just bruising and would clear eventually. I did have bruising, but that all cleared up within 2 weeks and I still have a grey "halo" 3/4 around the design, 6 weeks later. I now am scheduled to 'add' to it just to cover up the unsightly staining---which now will alter my original design! Can anyone advise me as to what caused this to happen? Also, would I be out-of-line to suggest a cut in price for the cover-up work?