Not an OS update, already checked that before posting.
The app thing sorta matches my theory, as I said, I have a Facebook app that syncs my contacts, and that was where I first saw the broken number. I disabled the sync function except for contacts that already exist in my phone, deleted her contact, and recreated it. This process seems to have worked, however I did a number of other things right about the same time, so I really don't know what it was that finally resolved the issue.
CrimsonStrife's post in Weird issue with a cellphone... was marked as the answer