Strange behaviour of MKMapView.SelectedAnnotations with MonoTouch

Question

In short, my problem is as follows:

I am adding somem custom annotations on a MKMapVIew. I want to be able to hide selected annotations when i move the map. To do that, i used the method of intercepting map touches as described here: http://stackoverflow.com/questions/1049889/how-to-intercept-touches-events-on-a-mkmapview-or-uiwebview-objects.

The problem is that when iterating through MkMapView.SelectedAnnotations i get different types of objects:

a) When running the application in the iPhone Simulator (Debug/Release) and on the Device(Debug) SelectedAnnotations contains MKAnnotationVIew objects;

b) When running on the Device(Relese) SelectedAnnotations contains MKAnnotation objects.

My question is if anybody knows why this happens. Is it normal behaviour, or am i doing somehting wrong?