This morning, I logged onto Google Reader and there was a note saying that Person X is now following me on Google Reader -- essentially, when I read something that I think others would be interested in, I click the 'share' button and that blog posts pops up in Google Reader for everyone else who's following me.
Anyway, in addition to the note saying Person X is now following me, there's a note asking if I want to follow Person X, so I click yes. I then send Person X an email saying ha ha, you sure you want to know what I read on the internet. It then became clear that Person X is only following me because I was following Person X -- the same reason that I'm following Person X, because Person X was following me!
Essentially, it seems like Google just decided to link us together even though neither of us initiated the following. I dunno, maybe we had exchanged enough emails or something to pass some threshold. But that's kinda creepy.