I doubt the hardware problem as well. It possibly was just a one time flaw as this trip was not even the first longer (+ 200 kms) one I made with the Moto G plus NextGen.
As for background processes, none that normal Android should have running all the time. I made sure no apps were running before start (plus greenified memory), set up the route, added car power supply and enabled positioning plus mobile internet (for traffic events, works great by the way). Thus apart from NextGen, no other app was or should be started/running, not even GPS-Status, that I "called for help" when the GPS signal was lost and wasn't found. So far, I neither have had issues when a sms or whatever announcement came through.
So either it's a NextGen thing or it was a rare (?) atmospheric(?) or magnetic? ?) disturbance perhaps?
I have no idea.