Mr. Monk and His Biggest Fan - S6-E1
Plot hole: It's out of character for Monk, a chronic stickler for details, not to correct an error, especially one relating to his own life. Marcy's diorama for "Mr. Monk & the Three Pies" includes Natalie, who wasn't around yet when "Three Pies" occurred. The doll should be of Sharona, but since that would ruin the ensuing joke, Monk is allowed to overlook it. He's aware of Marcy's unreasoning obsessions, but Monk's OCD would simply not permit him to keep quiet about a mistake that glaring.
Answer: Notice also that in the opening credits scene when he is touching parking meters her also wipes his hand on his clothes each time he does it.