Sony has issued advice to PS3 users that have seemingly 'lost' Trophies due to yesterday's calendar-related system bug.
'It is possible that some users who experienced the connection problems yesterday and tried unsuccessfully to access a game (online or offline) may find that trophy data for that title is no longer displayed.
'To resolve this issue, the user will need to re-access the game to reinstall the trophies, then exit the game and sync their trophy collection to the server in order to regain previous achievements.'
So there you have it. I do know many were worried about loss of trophy data. But that's the easy work around if you do have issues (usually with the last game you played, or have not sync'ed for a while). ROCK ON !!!