So, here's what Pentax US e-mailed me back:
Yes, this can be fixed under warranty, assuming you have not physically abused the camera (no cracks in the camera, etc).
Unfortunately, the normal repair time is about 4 weeks from the time we get the camera until the repair is complete, and this does not count shipping in either direction.
I could issue a call tag for you and have UPS pick the camera up from you, but that usually adds time to how long it takes for the camera to get to us.
So, over a month with no camera if I want this fixed.
Of course, the pixels don't show up in bright areas, and are unlikely to be visible at small print sizes. And in dark areas they're usually pretty easy to touch-up if it's in an essential area. But, it's still really ugly.
It's pretty frustrating that there's no in-camera solution for this, and even more frustrating that the turn-around time is so long.