Actually, upon further investigation, I see that I'm having the same problem on SEVERAL of my upcoming event posts with this widget. Here are two screen shots that illustrate this problem (compare the event dates with those displayed in the widget above):
This isn't happening on EVERY event, however it is happening on close to 50% of them! I don't think the date syntax works in this code. I appreciate what it is trying to accomplish, instead of listing it in long form like the other mod out there, I really prefer the short format, but I don't think it works right. When the date is off, it is always off by exactly 1 day.
Is anyone using this with a site that posts a lot of events, and can you provide a link to your site so I can compare the widget dates to the actual calendar event dates? I'd be curious to see how this is working for other people.
What a shame! I really like this mod, and don't want to use the long form date range display.
Bummer!

Jeff