That's nothing to do with being logged in or not. That person has accessed those pages via facebook and allowed facebook to post that they have done so. If they had accessed those pages by going direct to them in their browser rather than via facebook, even if they were still logged into facebook, facebook wouldn't know they had read them and would not post about it.
Getting slightly pedantic, but if you're logged onto Facebook/Twitter/Google (so there's a cookie saved on your browser) and you visit another site that's linked to e.g. Facebook, for instance by embedding a tracking image/script, then Facebook may know that you've visited that site even if they keep quiet about it.
Given the ubiquity of Facebook/Google it's possible they'll track you even if you don't have an account with them, simply by setting a cookie, though I vaguely remember an article which suggested they may have stopped doing this.