If you're putting your game on pause frequently, this can happen. Right after you get an event, check your game log for an entry similar to this:
Thu Mar 12 09:56:38 2007: Triggering event in block 4. Current time is 432974, next event at 476174.
That is the time in seconds. Subtract the first number from the second number and divide by 3600, which gives the number of hours until the next event. Add those hours to the time stamp, and that will tell you when to expect the next one.
If the game is on pause when the event is due, then I'm afraid you miss it.