I have an 06 Rendezvous also, and the car is supposed to do this. Higher end cars have had this feature for quite some time and I was suprised to find it in a mid level Buick. When you turn the key, the car automatically takes over and continues to turn the engine over until it starts or 5-7 seconds go by. Usually the car starts by this time unless there is a problem. This is a normal feature in and of itself and does not present a problem. GM has had this feature standard on Cadillac, Olds Aurora, mostly the high end stuff. They have been filtering this feature down.