Hay, I have a 2005 G6 GT and it does the same thing.. i have taking it to the GM dealer here in town and they first said that it had to do with the started cuz it runs on its own computer, and then some to find out thats not it.. then they said it does it becasue the car does not know if it wants to start warm or cold. I took it to another garage and they said to try the fuel presser sensor.. So i tried that and have no had any problems starting.