Hours in Qt.formatTime doesn't work with Date(milliseconds)

See the code below for the error.
I build a javascript Date with 3600000 milliseconds (http://www.w3schools.com/jsref/jsref_obj_date.asp)
Then I get the hour with formatTime. It returns 2h00 and not 1h00.

If I set the Date with 3600 milliseconds, formatTime returns 1h00 (I guess that there is a mistake between seconds and milliseconds in the format)

import QtQuick 2.0

Rectangle {
    width: 360
    height: 360
    function f()
    {
        var d = new Date(3600000);
        console.log(d.getTime());
        return Qt.formatTime(d, "h'h'mm") // return 2h00
    }
    Text {
        text : f()
        anchors.centerIn: parent
    }
}