I did change one setting on my device, or rather in one of my apps. In my podcast catcher, I disabled automatic downloads, and streaming performance has become noticeably better. That actually should not have mattered, because I had the podcast app set to download episodes only when connected through wifi; then again, the app in question is quite notoriously buggy. Be that as it may, I've just been out walking for 45 minutes, and streamed a radio station for the entire time without any stalls or buffering. What's more, the station in question is one that has always been particularly difficult to stream, to the point that in the past I"ve often been unable to stream it even when other stations worked fine using the same app (TuneIn).
As I said, I don't know if the changes I made have anything to do with it, or if it's just the weather.
Or maybe Sprint has really been upgrading the towers in my area...