That is correct. You have until your factory warranty expires. Just make sure it is a GM Protection plan and not some after market plan. As you are aware you can raise the deductible to reduce the cost. Believe the plan comes in $50, $250, $500 and $1000 deductibles. Something else to consider is the fact that the warranty is transferrable (small fee) should you decide to sell the car. Good selling point. You might check the link for further info:
http://www.gmprotectionplan.com/glossary.html