Random events can only spawn at 5-minute intervals (when the login timer reads 05:00 - 05:10), but the estimate in the plugin does not round up to these intervals. For example, if you have 2:30 remaining as the estimated next event and then hop worlds, the actual next earliest time you can get an event is at 5:00, but the plugin estimate does not update to reflect this.
Update the plugin estimate either based on the login timer (if that information is accessible) or jump it to the next 5-minute interval whenever the player logs off or hops worlds.