JUSTIN BIEBER'S mom, PATTIE MALLETTE, recently went out on a date with CHRIS HARRISON . . . the host of "The Bachelor" and "The Bachelorette".  And it was RYAN SEACREST who set them up.

--After the date . . . which was to a Justin Bieber concert . . . Pattie Tweeted, quote, "Had a great night w @chrisbharrison! Thanks @ryanseacrest for setting it up."

--Ryan replied, quote, "Does he get a rose?"