Repeater's count and itemAt() not always correct

import QtQuick 1.1

Item {
    width: 640
    height: 480

    Column {
        anchors.centerIn: parent

        Repeater {
            id: repeater
            model: 4
            onModelChanged: printWidths()
            delegate: Rectangle {
                color: "red"
                width: (index+1)*50
                height: 50
            }
        }
    }

    Component.onCompleted: printWidths()

    function printWidths() {
        print("Repeater has " + repeater.count +  " items")
        for(var i = 0; i < repeater.count; i++) {
            var c = repeater.itemAt(i);
            print("Width of item " + i + ": " + c.width)
        }
    }

    MouseArea {
        anchors.fill: parent
        onClicked: repeater.model = 7
    }
}