Facebook App URL Issue

I have an FBML app and a strange thing keeps happening.

If I go to http://apps.facebook.com/myapp/page2.php

I just get redirected to http://apps.facebook.com/myapp/index.php

It always goes back to index.php even though I specified page2.php and it is in the URL. This doesn't happen to my iframe apps.

Does anybody know why it's behaving this way?

htaccess rewrites

Seems like making the canvas callback URL http://WWW.example.com rather than just http://example.com fixed the problem.

But why???