Aha, that would explain things and also gave me an insight into how pgc actually works.
This would explain, I assume, why a recent logg that was edited just shortly after it was placed did not trigger a notification. This would be so since a notification needs two cache renewals at pgc, one after the logg was placed, then another after the edition.
This would also imply that I can trigger a notification from a cache by placing a little note logg on the cache (but without deleting it right away since that note would go unnoticed from pgcs point of view).