2010 Nissan Frontier Rough Idle

My 2010 Frontier idled very smooth, warm/cold until it hit 900 miles. That morning on startup it went to fast idle like normal but immediately there was intermitent roughness. Enough so that it was very noticeable and as the idle slowed to normal the roughness still remains but not as harsh once at operating temperature. The roughness is very patterned: approximately 2 seconds smooth, 2 rough. Took to dealer today for first oil change and they said the idle had to be reprogrammed (relearned) Idle still rough and this certainly takes the wind out of a new car purchase. Thanks for the assistance.