Was in cruise control and lost all momentum? (tranny issue?)

Ommateal

I was in cruise control on the highway, 6th gear.... then all of the sudden, it was like the car was in neutral.... pushed the gas and it reved but no grab or forward momentum, shifted down to 5th, nothing... Pulled off the side of the road.... went to neutral waited a second, put it in first, it moved now, then checked all gears again and it was fine... Got back on sped up, went back to 6th and cruise... went to work. not a single problem the rest of the ride? WTF happened? Did my tyranny just decide to not work? There were no noises, nothing sounded broken. I just purchased it used about a month ago.

I know thats not a lot of info. But best guesses are nice?

2010 sport 6m, 41,xxx miles.

It is still under powertrain warranty, how do I go about having it looked at?