How does "Require SSL" affect ASP.NET MVC application lifecycle?

Question

I have an application that taps into BeginRequest and EndRequest to set up and tear down NHibernate sessions like this:

BeginRequest += delegate
{
    CurrentSessionContext.Bind(SessionFactory.OpenSession());
};

EndRequest += delegate
{
    var session = CurrentSessionContext.Unbind(SessionFactory);
    session.Dispose();

    Container.Release(session);
};

This works fine when deployed in IIS, until I check the "Require SSL" box. Once I do this, I get a NullReferenceException at session.Dispose().

I haven't debugged this yet and, yes, the fix is trivial, but I'm just curious about how "Require SSL" affects the lifecycle of a request. Is a session not set up on the server in these cases?

EDIT: Just to clarify, I'm referring to the "Require SSL" option in IIS configuration for the application, not the RequireHttps attribute for controllers.