Running "sync" fixed it:
[root@lenovo-pc ~]# sync
[root@lenovo-pc ~]# debugfs
debugfs 1.44.6 (5-Mar-2019)
debugfs: open /dev/mapper/fedora-root
debugfs: icheck 345053591
Block Inode number
345053591 86246540
debugfs: quit
[root@lenovo-pc ~]#
The "find" command identified it as an old file in my home directory that
hasn't changed in 11 years. I have everything backed up on the other machine, so
copied the file back from there. After doing that, the "Current Pending Sector
Count" went from 1 to 0. The "Uncorrectable Sector Count" is still 1. A
short smartctl test was successful.