Here is an example of what I am getting at. The following is a post occurred after Tom Merritt (someone in one of my other circles) showed up in my stream AFTER Tom and Roger Chang held a private Google+ hangout https://plus.google.com/u/0/103207773865797007066/posts/L4Mqhncvuyt . It appears that there is no way of having this type of post not show up after one holds a private hangout. I was not invited to this particular hangout between Tom and Roger.