No.
Microsoft's warranty is a 1 year standard warranty. The best buy warranty you have is a 2 year extension to MS' warranty. There is a provision with MS where they will cover a specific failure type that is denoted by 3 red quadrants on the Xbox 360. Your warranty breaks down like this:
(1) If you have any kind of failure in the first year, BB can require you to return the Xbox through Microsoft's channels. Some Best Buy stores will not enforce this and will allow you to replace your Xbox at any time.
(2) If you have a non-3RROD failure during the next two years (years two and three after you bought the 360), you can get it replaced using the best buy plan.
(3) If you have an 3RROD error at any point, you are supposed to return the Xbox to Microsoft. The Best Buy warranty is not suspended for this specific error type, and by the word of their agreement MS covers this type of error and therefore you should return it to MS.
The short answer is because you have the BB warranty, you're fully covered for three years of ownership.
