the car in question: (more or less) with the DCT (yes that one)

on the highway I went to pass and I couldn’t get any more power. I dropped down a gear and same thing. It held the RPM’s constant almost like cruise control was stuck (i don’t use it). accelerating was super slow even from 1st. It was acting as if I was trying to start from a stop but was in 5th gear. I stopped off at a store and it was back to normal after that. Any ideas? It was unusually cold this morning.