Transmission hiccup??

So I've got a 2018 S3, 15k miles and I'm having an infrequent and weird occurrence where the transmission will slip out of gear and free revs till I let off the accelerator and then it re-engages. it's happened in 'manual mode' and auto (I don't drive in dynamic). yesterday it happened while I was trying to reverse up a steep incline which was very concerning as it allowed me to roll 3 feet almost into a parked car.
Anyone have a similar experience?