Web.config change does not auto-restart application

I am using IIS 7.5 on a Windows 2008 server. I am trying to take advantage of Application Initialization Module (http://www.iis.net/downloads/microsoft/application-initialization and http://blogs.iis.net/wadeh/archive/2012/05/01/application-initialization-part-2.aspx) to prime the cache.

After I installed the module and configured the appPool to AlwaysRunning and the application to preloadEnabled, I can see that recycling the process triggers Application_Start and the cache gets preloaded.

But, if I change the web.config, I can see that my app gets unloaded, but I don't see it being loaded again - Application_Start event is not being called. 

What am I missing? Shouldn't a change to web.config trigger the app to be restarted when Application Initialization Module is configured to auto-start the application?

Thanks.