Automatic Transmission problems of the 2008 Lexus ES350

I was making a right turn onto a busy street and accelerated hard with my 2008 ES 350 Lexus. After accelerating to 45mph I stopped applying pressure to the accelerator pedal but the car continued to accelerate up to 80mph while going up hill and my foot was completely off the accelerator pedal. I tried to see if the pedal was stuck by lifting the accelerator pedal with my foot but the car continued to accelerate. I was approaching an intersection and used both feet to apply firm pressure to the brake pedal. I was able to stop the car although the engine was idling at a much higher rpm than normal. I did not experience the situation again on the remainder of my 20 minute trip. I did not have my winter driving mats in place when this occurred. I did not report this to Lexus although described my experience to CO-workers that same day. Based on recent news reports I formally notified my experience to Lexus customer service today. I explained that this problem had nothing to do with the accelerator pedal getting stuck on a floor mat.