general problems of the 2007 Acura RDX

I had two events. One while driving at 20 mph in my neighborhood and straight line driving and car suddenly accelerated. I threw car in neutral and stepped on gas hard for a second and cancelation stopped. Then five minutes later, while making a left turn, same exact event took place. I did the same thing. I had the brakes on hard and no stopping car. First time car has done this and I am only driver for six years. Brought to Acura and they sent a corporate mechanic to check and said they found nothing. Just got car back. A little scary.