Running "hdparm --read-sector 3299402936 /dev/sda" according to
https://www.smartmontools.org/wiki/BadBlockHowto shows that the formerly bad sector is
readable, so I'm not sure why the "Uncorrectable Sector Count" is still 1. I
don't want to force it to be marked as a bad sector unless I'm sure it actually is
bad - if the error happens again with the same sector, I can always mark it as bad later.