Trivia: The day this episode aired, March 3, 1966, Alice Pearce (the first Mrs. Kravitz) passed away. The episode was interrupted to announce her passing.
Disappearing Samantha - S2-E27
Trivia: The person who plays Darrin's client in Disappearing Samantha is the "Witch Doctor" in the following episodes.
Follow That Witch (1) - S2-E28
Trivia: Alice Pearce (original Gladys Kravitz) died of ovarian cancer in March 1966 before this episode aired. Abner's sister played the foil in place of Gladys, who would later be replaced with another actress for remainder of the series.
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