American Dad and Family Guy work just like The Simpsons. Multiple episodes of their season order get delayed or Fox decides to air the next season.
For example, the newest Family Guy episode "Back to Woods" was the first episode of the season 6 cycle, although Season 6 is airing right now. The intended season finallie of Season 5 was "Lois Kills Stewie" (And the second part would've been the season premire, ala "Who Shot Mr.Burns"). Also, Blue Harvest was intended to air in May (Coinciding with the 30th anniversary of Star Wars, though it was probably delayed because they xtedned the ep to an hour).
Plus American Dad still has episodes left on its season order (according to wiki at least)