This is a Gen 13 Chromium which only came out of the red and/or black sealed boxes. Some of the Chromiums were signed by Jim Lee and some were signed by J. Scott Campbell. All of the signed copies I have seen have been signed in gold ink pretty much exactly like that. So, if the gold ink sig is on the slab, then they have done a great job of simulating the signed book.
But if it is on the book then that leaves me with one of two choices:
(1) It is a mistake or
(2) CGC has decided that since they were "produced" by Image with the signature on them, the signature will be ignored.
I believe that it is #1 not #2, if the sig is on the book.