At the moment it shows the birthdays/events a week in advance. This is acting as a reminder in case people would like to plan something that co-incides with the event. I'm not sure how many days it remains there afterwards as I haven't looked at the settings recently.
To see the "real" date for these events, you need to click on the small calendar icon to the left of this area or open the calendar using the menu button at the top of the forum index page.
I can change the settings if members are finding it too confusing.
