At first I was terrified that all my old CDs had started to disintegrate, but the CD played fine in both my stereo and on my computer, which indicated that neither the disc itself nor my laptop’s optical drive were the problem. Re-ripping the CD in iTunes with error correction on fixed some of the files, but not all. I ended up re-ripping it again with XLD and this solved the problem as far as I have been able to determine. Which means that iTunes is probably the culprit.
On the other hand, in the process of getting to the bottom of this mystery I have listened to the recording at least twice now with quite close attention due to listening for skips and jumps, and I can certainly say that I still like it.
Also, I hear that Joyce DiDonato’s new recording is pretty good. Perhaps some day the US mail will deliver my copy of it.