I just noticed this feature on my phone last week. I have been actively using multiple Google Calendars via CALDAV and it worked perfectly in PR1.2. Even all the past events synced as I wanted to. Last week I noticed the past events are missing and I removed the CALDAV account and readded it to fix the issue. Ok, then the future events farther away than about 6 weeks stopped showing. So future events worked fine for me in PR1.3 until that. The workaround works, but I wouldn't want to use it after each sync.

However it seems that this is not just about the CALDAV. Events added to the local default calendar are also hidden after a reboot or a CALDAV sync. I think this bug has something to do with the way the calendar application refreshes the calendar view after boot or sync. It would be nice to have someone to report the bug to. I wouldn't want to reset settings or reflash the device just to try if the problem would be gone.

As if the future items sync/display issue isn't enough, I now get a message that my memory is full after caldav syncs my calendar... When I look in the settings there is only 1kb used by the calendar application and there is still 1,7GB of free memory for applicationdata. Really annoying.

Interestingly I just had the same error message for the first time today. I rebooted and resynchronised and no further message so far... but I agree there was no reason for that. I even went to my google calendar to see if the message was from Google but nothing apparent there.