To reproduce:
1.Create a RadRibbonForm and add a QuickAccessToolBar and a Contextual Tab Group
2.Use the following code:
public Form1()
{
    InitializeComponent();

    this.AllowAero = false;
    radRibbonBar1.RibbonBarElement.IconPrimitive.Visibility = ElementVisibility.Visible;
    ThemeResolutionService.ApplicationThemeName = "TelerikMetro";
}
3.Run the application. Position the QuickAccessToolBar below the ribbon via the drop down menu. Note that the Contextual Tab Group is shifted to the right.

Workaround:
this.radRibbonBar1.QuickAccessToolBar.RadPropertyChanged += QuickAccessToolBar_RadPropertyChanged;

private void QuickAccessToolBar_RadPropertyChanged(object sender, Telerik.WinControls.RadPropertyChangedEventArgs e)
{
    if (e.Property.Name == "QuickAccessToolbarBelowRibbonProperty")
    {
        if (this.radRibbonBar1.RibbonBarElement.QuickAccessToolbarBelowRibbon == true)
        {
            this.radRibbonBar1.RibbonBarElement.RibbonCaption.Margin = new Padding(-15, 0, 0, 0); 
        }
        else
        {
            this.radRibbonBar1.RibbonBarElement.RibbonCaption.Margin = new Padding(0); 
        }
    }
}