Samantha's Witchcraft Blows a Fuse - S8-E25
Revealing mistake: When Darrin brings the ladder around to the front of the house, it's obvious this is not the actual house but a stage set; the background is obviously a painting and the driveway/garage have disappeared. Further the outside and windows are too narrow to be the actual house. The den is larger than the small facade in the scene.
Samantha's Witchcraft Blows a Fuse - S8-E25
Revealing mistake: When the officers pull away, the shadow of the car is visible on the painted backdrop of trees. This isn't the neighborhood of Morning Glory Circle with the Kravitz House across the street. The shadow reveals it's a stage backdrop. Further, this is basically the same as Allergic to the Macedonian DoDo Bird from Season 3, with the same DoDo Bird costume.
Answer: Larry had been telling Darrin what it means psychologically that Samantha gave the coat away. Larry said giving it away meant she's happy being married but if she liked the coat it means she desires to be single and carefree. So when Darrin sees the coat, he immediately thinks Samantha doesn't want to be married and the fact that she twitched it means (in his mind) she wants to be a single, carefree witch again.
Bishop73