Nope. Johnny's final appearance was on Letterman's Late Show on CBS. Late Show was visiting Los Angeles for a week and Johnny came by on Friday with the Top 10 list.
From Wiki:
Post-retirement appearances
At the end of his final Tonight Show appearance, Carson indicated that he might, if so inspired, return with a new project, but instead chose to go into full retirement, rarely giving interviews and declining to participate in NBC's 75th Anniversary celebrations. He made the occasional cameo appearance, including voicing himself on a 1993 episode of The Simpsons ("Krusty Gets Kancelled") and appearing in the 1993 NBC Special Bob Hope: The First 90 Years. On May 13, 1994, Carson appeared on The Late Show with David Letterman. During a week of shows from Los Angeles, Letterman was having Larry "Bud" Melman (Calvert DeForest) deliver his "Top Ten Lists" under the guise that a famous personality would be delivering the list instead. On the last show of the week, Letterman indicated that Carson would be delivering the list. Instead, DeForest delivered the list, insulted the audience (in keeping with the gag), and walked off to polite applause. Letterman then indicated that the card he was given did not have the proper list on it and asked that the "real" list be brought out. On that cue, the real Johnny Carson emerged from behind the curtain (as Letterman's band played "Johnny's Theme"), an appearance which prompted a standing ovation from the audience. Carson then requested to sit behind Letterman's desk; Letterman obliged, as the audience continued to cheer and applaud. After some moments Carson departed from the show without having spoken to the audience, later citing acute laryngitis as the reason for his silence.