Well, I got a CEL on the drive home yesterday. Not too surprising, seeing as that I was getting long term fuel trims of 25.
I cleared the code (P0171), but unfortunately, that also reset the LTFT.
I was worried that I'd have a hard time starting the car with LTFT at 0, but it started normally this morning. By the time I got to work, LTFT was back to the 17 to 23 range, and STFT was around 0. So the ECU adapted in about 20 miles or so.
Also, interestingly, as soon as I cleared the code, the idle smoothed out noticably. I also though the throttle response improved.