This issue is really the only roadblock that I've got to the GSync app working for me on the Blackberry.  I'm usually able to just grab the appointments from the Trash and put them back into my calendar, but it is a giant pain to keep doing.

Strangely, these events aren't removed from my Google Calendar, just from Outlook/Exchange.

I would also classify this a bug.  The sync client just needs to not worry about calendar items over the "older than" threshold rather than deleting them.