Sometimes calendar items will come in with a created date of 0000-12-29T00:00:00.000Z. I've got it with a few of my own calendar items, and there's at least one other person who has that issue:
This causes ParseCalendarItem to fail because the year in the above date is zero, and EncodeDate requires year to be at least 1. I'm not really sure why Google is sending over calendars with that created date, but it's probably worthwhile coming up with a workaround. I manually modified CloudGCalendar to catch the conversion exception and merely assign the creation date to the updated date if creation date is 0 so the rest of the calendar can be parsed and loaded.