There are actually two leap day souvenirs for 2016. One of them was awarded for attending an event on leap day (and is sorted as an event-related souvenir) and the other was awarded for logging any geocache on "leap day weekend" (and is sorted as a specific-day souvenir). Many if not all of the souvenirs in the event category also require logs on specific dates or during short time periods, so the convention is to sort as an event if relevant and as a specific day as a secondary option.
