Turns out that while the retail box drives are only warranted for a year, the OEMs carry a 3-year warranty. I'm glad I build my PCs from parts.
I had bought a spare online, but UPS had thrown it over the patio wall so I did not want to keep it. So at lunchtime I went to UPS, refused delivery on the purchased drive and shipped the failed drive to WD. That'll net me about $125, and I'll wind up with a good spare.