During the second season, the narration changed it to them being “simply friends,” and the "sometime earlier" narrative was also changed to "several years earlier.”  Later, in an episode aired in 1973, the two were in the Army together, with Felix being Oscar's superior at the time Oscar and wife Blanche (Brett Somers) married. An episode aired in 1974, the epilogue showed Oscar's recollection of meeting Felix when they were children.
The narrative about the relationship between Oscar and Felix evolved over time, shifting from "sometime earlier" to "several years earlier."  This shift was reflected in both the narration and the storyline itself. The episode featuring them serving together in the Army provided context for their past connection.