Changing month or year not updating text input properly

[waltzonice]

I am playing with your first example on your datetimepicker webpage (Add a simple datetimepicker to jQuery UI's datepicker). I click in the empty text box (datetimepicker appears showing August 2013), then click on the "next month" button, the text box now shows "12/31/1899 00:00", even though the datetimepicker now shows September 2013. I click the "next month" button again, and now the text shows "09/08/2013 00:00" , when the dropdown shows "October 2013". It appears that when the month or year is changed, the datetimepicker is incorrectly setting the text to the previous value, and not the new value. Is this a bug?

[waltzonice]

I want to add that this only happens when you start with an empty text box. Once there is a datetime entered into the textbox, reopening the datetimepicker will pre-populate correctly and changing the month/year will have no effect on the input box (consistent with how the jQuery datepicker works -- changing only month/year does not change the textbox, only changing the date will actually change the textbox).