Earlier in the episode, Frank stops in to get his mail, and Estelle brags that Kramer made a pass at her. She tells him to take his mail and go home, implying that he is staying elsewhere. However, at the end of the episode, after Frank leaves the proctologist's office, George brings him back to the house, and Estelle starts raving about how worried she was that he hadn't come home yet.
NOTE: When Frank arrives, Estelle says, "Where have you been, you were supposed to fix the stove!" In other words, he has not "come home", he is only there for that one purpose.