Rickey Minor -- who has been the bandleader for 6 seasons -- is leaving A.I. to head up Jay Leno's band on "The Tonight Show."
Minor was fit to be tied after no one thanked him or wished him well -- hell, they didn't even acknowledge him during last night's finale.
Our "A.I." spies tell us ... when the show was over Minor went off on producers, angrily telling them how insulted he was by their silent dis.
Minor refused to go backstage for the champagne afterparty. But producers pleaded with him and then got Randy Jackson to try and smooth it over with an unprepared speech.
Minor then said a few words but we're told, "You could cut the bitterness with a knife."
We're told Minor recanted and went to the afterparty -- but he was still fuming mad.