Sort of hearsay, but anyway...I don't keep any rabbitfish, but hang around the fish disease forum a lot. Its very common to see folks concerned over this type of coloring in these fish. The people who know them then always reply that this normal. I agree with some of the posts above; I doubt DD would ever post pics of problem fish without a disclaimer. They do occasionally offer fish with nothing more than a harmless odd color patch, etc.; but always state that this is the case. They are the gold standard in their field, IMO & IME.