What's the cause of this iOS error?

I've got my navigation setup as follows.

    public static INavigation Navigation { get; set; }

    public static Page GetMainPage(IContainer container)
    {
        var rootPage = Container.Resolve<MainPage>();
        return rootPage;
    }

public class MainPage : MasterDetailPage
{
    public MainPage ()
    {
        Title = Strings.app_title;
        var master = new MainMenu(OnAfterDeauthenticated);
        var detail = new NavigationPage(new ModulePage(OnToggleRequest) { Title = Strings.app_title });

        if (App.Navigation == null)
        {
            App.Navigation = detail.Navigation;
        }

        Master = master;
        Detail = detail;
    }

I've done this to avoid that irritating exception in Android, but now every once in a while, when I'm navigating in iOS, I get the following exception.

2014-07-08 14:41:40.654 FutureStateBreathingRoomiOS[632:60b] nested push animation can result in corrupted navigation bar
2014-07-08 14:41:41.036 FutureStateBreathingRoomiOS[632:60b] Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.

What's the cause of this, and how can I fix it?