I had my first flat tire in my Prius today. I was about 3 miles from home when a heard a beep and a flash on the dash. It was so fast I did not know what had lit up. The car did not feel different. Once home I went to the garage and noticed the back drivers side tire as flat as can be. I filled it up with that tire inflator stuff and got it to our local gas station. They fixed it with no problem (hole in tire but no nail). Could the beep have been the car trying to tell me that the tire pressure was not right?