" GG added you back on Google+" April 14, 2014 One year!* And
  yes, you are correct.* If you added me back, that means I added
  you first. :P What likely happened: You probably commented on
  someone's post [perhaps in a community - probably Minecraft - or
  might have been a friend we have in common - I'm thinking Matt
  Cowen but I'm not sure now] - and I thought, "this guy's cool -
  intelligent - I want to hear more what he has to say about
  stuff."* Add to Circles.* Done. That's usually what gets me to
  add people; I can spot creativity/intelligence in a few words
  someone writes and ask myself, "More? Y/N".* If Y, then "Add to
  Circles".* If N, then I don't. I don't know the particular post,
  although looking back at email archives, the posting after that
  was a 3D view of a city in France.