Using request.now is _guaranteeed_ to go backwards once a year in most of the world (when going back from daylight saving time to standard time; the date this happens differs between countries).
request.utcnow, which I mentioned in my original post (and appears in the readme, but for some reason not in the code?) solves this problem as long as you trust your clock to never go back. But I don't trust the clock to never go back (based on real life experience).
