Unfortunately it's not a good sign when someone 'flakes out' for a good deal of time and doesn't talk to you for several weeks. In my experience it means that they aren't taking you as seriously as you may be taking them. It's happened to me before where I was 'kinda dating' a person and I knew they liked me, I hung on and waited, and ultimately found it would have been better if I had just blown them off.
As for the question you asked, I think that if a person like that called me, I'd probably just play it cool and not act too overly interested. I wouldn't bother confronting them, since often people that act that way hardly aknowledge it (in my experience at least). Maybe you could agree to another date or something if you'd really like to give this person another shot, but you've got to decide if it's worth being hurt emotionaly. Personally, I would back away and let the person contact me, that seems to be what you're doing now anyway.
Hope all goes well,
-J