A sharp right turn in the middle of writing a novel

Not many people remember Dorothy Johnson these days, but she was the master of the short story, most often about the American West, and the author of such stories as "A Man Called Horse" and "The Man Who Shot Liberty Valance." Years ago I was privileged to call her my friend and to correspond with her. In her later years (she hated the term octogenarian, which she said sounded like a scaly reptile with a skin disease), she was writing about New York City during WWII and the constant alert for fear of the bombing attack that never came. She titled it "The Unbombed," and I suspect she never finished it before she died. But one day she wrote me that she'd just had a terrible shock. She'd found out that the man she thought was going to be the hero of her book was going to be killed in the war. Who told her? Her muse. Dorothy was a firm believer in listening to your muse as you write.
Something similar happened to me today. When I woke up this morning I lay in bed a long time, plotting in my head the end of the novel I'm about halfway through. But I never was really comfortable about the murderer--he's a nice guy, and I hated to turn him into a villain. I finally made it to my computer to write down all the stuff in my head and happened to read an old file called rough ideas or something like that. In that, the villain was a totally different person and had a much more believable motive. So now I'm doing an abrupt right turn. I hadn't gotten far enough into the end that this is a serious problem, but it does call for minor revision. But I feel a lot better about the whole thing now. There are a lot of possible suspects, but now I know who really did it. Most writers will tell you to listen to your characters and they'll tell you what's going to happen, and I've had that experience more than once. I remember a writer who taught a seminar at TCU and said, "What is this nonsense about listening to your characters? I'm the author. I tell them what to do." I didn't much like his books.
My mystery of the day: how can you put four pillow cases in the laundry and only get three back? There's a poltergeist in my house!