Friendly Freddy, the Gentleman's Tailor - S4-E30
Other mistake: Gomer and Sargent Carter buy alike suits. They are together in the suits. Gomer doesn't start sneezing until he gets to Lou Ann's apartment and Sargent Carter doesn't start sneezing until Gomer mentioned the suits will make him sneeze. (00:10:33 - 00:18:36)
Answer: There's no indication they were meeting for the first time, in fact they seem to know each other as Sgt. Carter addresses Andy only as "Sheriff". Gomer Pyle just says his two favorite people are "meeting face to face", and obviously in the pilot episode Sgt. Carter wasn't one of Pyle's favorite people yet.
Bishop73