In the GTD book, it says that the calendar is the spot to put a task that must get done today or not at all. This item does not have to have a time slot associated with it on the calendar, but can be a day-specific (untimed) event. Continuing to use your calendar for this item would not go against the book in my opinion.
Some people would go a step farther and block out a timeslot for such things. This is optional and would probably not be advised by DA.