incorrect date set with setDate in jquery ui calendar

I have a weird situation with jquery ui calendar's setDate.

I have two date pickers - checkin and check out.

$("#checkin").datepicker({

    onSelect: function(date,dateObj){

        var selectedDate = new Date(date);
        selectedDate.setDate( selectedDate.getDate() + 1 );

  开发者_开发问答      $("#checkout").datepicker("setDate", selectedDate);


    }
});

let's say I have selected 6/1/2011, then checkout date should be 6/2/2011, but I get 6/7/2011.

Do I have an error within my code or is this a bug?

It seems to be working here:

http://jsfiddle.net/rt3nC/8/