I'd planned on having Marian turn 40 in Full Frontal Murder and even wrote some scenes about it. But her birthday got in the way of the story; there's a lot going on in that book, and the trauma of facing the Big Four-Oh simply didn't belong there. There was no place for it. So I cut all references to her birthday, planning to include the event in the next book. But of course there was no next book; so that leaves Marian, like Jack Benny, perpetually 39 years old.