Yes peanut butter balls do need to remain refrigerated to keep them fresh and keep them from slouching.
If you plan to consume the peanut butter balls pretty soon as within the same day then you shouldn't need to refrigerate them.
But if you plan to keep some for another day then yes do refrigerate them to keep them fresh longer.
Also when making peanut butter balls you need to refrigerate them for 10 minutes after dipping them in the chocolate before serving them or eating them.