TLA and Google's terms and supplementaries [0] seem pretty explicit: "Whenever you comment on, follow or +1 a page while logged in with your Google account" "This only happens when you take an action (things like +1’ing, commenting or following) – and the only people who see it are the people you’ve chosen to share that content with".
Nothing is being made visible that wasn't previously visible, it's just that content is now appearing alongside other stuff.