I suspect Googlebot may be replaying a sequence of requests recorded with the Google Toolbar.
I think the user specific token in the URL disproves that. It's more likely that they're just doing the discovery themselves. Otherwise googlebot would be responsible for massive data loss, as it goes around mistakenly replaying delete requests on behalf of toolbar users...
What makes you think that isn't a toolbar users token?
I tracked down an issue with a friends (poorly written) shopping cart software duplicating a users order because Googlebot had crawled the users checkout session URLs in order. In that case I believe they were looking for differences in page responses to users and crawlers to detect cloaking (but that is just a theory for the behavior)