Don't fix storage leak this time

I have a 5220, NBU 7.5.0.6, I'm monitoring the Spoold.log and this entry is showing multiple times, What does it mean?

July 29 23:47:42 INFO [1082194240]: processDoSoTRefCheck: Don't fix storage leak this time, because so[20a711762cc8b917f2d7c7b6739e08e9] was protected by TLogID.

July 29 23:47:42 INFO [1082194240]: 25002: processDoSoTRefCheck: Storage Leak find. Could not find DO digest[f9a959c6ad074982356a011f4d25edc0] referenced by SO digest[21523dfba92bb66924b0102a

Thanks

Pat