Check Engine Code P1870?

So I was on the return journey from Rochester NY, I live about 200 some odd miles south in Pennsylvania and my "Service Engine Soon" light showed up about 60 miles down 390, this was the second time making this trip that day, so I was on roughly hour 5 of driving.  I stopped twice and checked up on the oil and other fluids and everything seemed fine, but I was still concerned over the lights sudden appearance and stopped at the next possible exit about 10 miles away.  I found an Auto Zone that was open, it was a Sunday so my first few stops were not open.  The guy at auto zone ran the scanner and came up with P1870 DTC (check owners manual).  I looked online and found that P1870 has to do with transmission slippage but can have a number of causes or factors.  Notable features about my driving that day were miles and speeds in excess of my normal work commute which is about an hour drive each day.  I was posted up in-between 70 and 75 mph consistently both to Rochester and back and had for the first time since I purchased the car made use of cruise control.  I also just hit 100k miles that day with the car.  I've dropped it off at the shop in hope of a more specific diagnosis.  My question however is in regards to the "Service Engine Soon" light, after realizing my only option after 4 on a Sunday was to continue my drive home and keep my fingers crossed, I got back on the highway.  I kept my speed down around 60-65 and did not make use of cruise control again.  The light went off after about 20 minutes of driving and has not come back on.  I was under the impression engine codes like that would not just go away and because it did I was wondering if my speed and use of cruise control could have been contributing factors, (I'm under the impression the MAF sensor can be one of the specific triggers for P1870) and if that is the case should it still be as big of a concern?