Dear Lazyweb, under what circumstances would a post that I can see in my Facebook stream not be available in the graph API?

I can't tolerate using the Facebook web site, so I convert it to an RSS feed so that it all shows up in my feed reader, but posts by certain people are being left out and I can't figure out why. E.g., for one of my friends, I can see their posts on other peoples' walls but none of their other posts. For their stuff, "https://graph.facebook.com/<friend_uid>_<post_id>?access_token=<token>" gives me false, but that same style of URL seems to work for lots of other people. These entries also don't show up under "https://graph.facebook.com/<friend_uid>/posts?access_token=<token>".

On the site the post has a URL like "https://www.facebook.com/<friend_name>/posts/<post_id>" and just says "N hours ago near Location" and the mouse-over says "Shared with: Firstname's friends" so I don't see what's weird about it.

WTF?