Yes and no. You can look at the xml stream to figure out when an event was deleted and recover its data. Go to your Google calendar, Calendar Settings, Private Address, XML, a link will popup, use that link in a browser and add "?showdeleted=true&showhidden=true" at the end of the URL. The XML is a bit difficult to go through, but you can see the <updated> tags and figure out when your cancelled event actually got cancelled.