I have experienced this from time to time in mine. I have owned the car for 2.5 years and have 43,000 miles. It usually happens at around 45 mph. It will last for about 5 to 10 seconds and do it 2 to 3 times. I won't experience it again for a couple of months and it will happen again. This has happened since the car had about 3,000 miles. I have learned to not stress about it. And will usually speed up if I can and then the episode is over.