I tried to set a reminder more than 4 weeks in the future. The reminder would appear correct with the mouse-over, but the alert flag would be active, i.e. as if the time had passed. Upon saving and reopening the map, the reminder was set to todays date. I tried every conceivable way of setting a new alarm, and it just didn't work. I only could get it to "work" by setting the reminder at April 21nd or earlier (today is March 27). Any date later than this would not work.
that's freemind 1 RC2