[Ralath]

You mean because you can go back a lot further with the timeline?

Or they actually changed the view permissions?

Both.

I think all your posts past a certain date become viewable to all your friends.

Well. It's complicated. So all the posts made before Facebook came up with these privacy settings become viewable by everyone. But there's a function that turns all your posts into only viewable by friends. However, if you have certain filters on your posts (like I do) where you've blocked certain friends from seeing some things, it turns those filters off.