Scott,

I dont have the Sprint warranty coverage, but Sprint still replaced mine. I bought mine from Sprint.

It is a manufacturer's warranty I think, but I'm not sure when it expires. I had my phone for about 5 months and they replaced mine with a "refurbished" one. The replacement phone has a 90 day warranty.

I would take it in to a BestBuy or Sprint store and have them check it out. The first store I went to didnt think my phone had a problem, the second one replaced it no problem. So try multiple locations.

It all depends on how bad your screen is I guess, some are worse than others. It seems that your BestBuy extended warranty should cover any significant screen defect, especially if you can compare it to an in-store display that doesnt have the defects.