Chalk it up to the infamous cutting room floor of revisions
. I had written a scene where Bones first saw Cat's tattoo and his reaction to it. Originally it was at the GiGi club, and Cat had taken off her bridesmaid dress to fight the vamps because it wasn't flexible enough. So she was in her bra and underwear when Bones came in, and thus, he had a clear view of the tat. But, the scene got amended to where Cat kept her dress on - blocking the view - and then Cat and Bones hunt down the other vamps there, so the tat doesn't come into play.
Then, the first time they get to it (heh), Cat's still wearing a dress. The second time is off-page, so the reader doesn't get a detail of Bones's reaction when he sees the tat. It's just how that worked out.
Oh, and the tattoo on Bones's arm on the book trailer is NOT how I picture his tat, but I wasn't going to make my then-web designer redo it. Bones's tattoo is not filled in, it's just an outline of the cross bones. One day, I will have temporary tattoos made from my image of Bones's tat, and use them as giveaways (but not for a couple months, folks. Time/money constraints and all that