First of all, thanks for all of the suggestions and responses.
I spent about an hour on the phone this morning with Apple support, and I have found a solution. Not sure why it suddenly sprang up when I restored from a backup on to my replacement iPhone 5S when it had never shown up before - including on my original iPhone 5S that I restored from the iCloud backup immediately after I got it.
A quick bit of background. I have only had one iTunes account. Early on I used a different email address as the login "name". About 3 or 4 years ago I abandoned that email address and changed the email address on my iTunes account to reflect the new address. Fast forward 3 or 4 years to today and suddenly I have a couple of songs that were purchased using that email address on my same iTunes account. I was being prompted for the password for that original email address, which was really confusing. It?s the same account.
The second iTunes account was my daughter's. Apparently she somehow managed to get 2 albums that she bought into my iTunes account... and my wife added a couple of songs to a common playlist. iTunes was (correctly) prompting me for authorization to access those songs, even though I never listened to them or added them.
In the course of talking with the 2nd level tech, I did managed to discover how to identify the culprit for future reference. If it?s an app, it simply will not update... it will continue to show as having a pending update. Easy, peasy.
Music, however was a bit more difficult to identify... until the tech showed me the secret. Here's how to identify the purchasing iTunes account for all music in your iTunes library:
- Launch iTunes
- Click the Music tab
- Right click (option click) on the headings above the music (but below the Column Browser section)
- Choose KIND - now your music is sorted in kind (MPEG Audio, AAC, Purchased AAC, Protected AAC, etc)
- Now scroll down to the section labeled Purchased AAC
- Right click (option click) and choose Get Info
- In the middle part of the popup info box, on the right side, there are 2 fields labeled: Purchased By and Apple ID.
- Scroll through that section (Purchased AAC) of your iTunes library by clicking the NEXT/PREV buttons looking for songs that don?t match your own AppleID. These are the songs that could be problematic.
Once I found them, it was simply a mater of deleting the offending songs from the library/playlist and resyncing my phone.