Someone registered a facebook account with my email address?!

I just got a weird email saying that my new facebook account has been set up and to verify it and then I got more emails saying I had two new friends. I am not on facebook at all and have changed the password for my email account as soon as I had read this. It is a relatively new email address and it is not a scam as the emails and links are genuine.

The link to report unauthorised email address use has apparently expired, what can I do? Is this because someone has the same email address but with a . in between or something like that?

Just as I was about to submit this, I have an update: I clicked on the activation link I received in the second email just to see what would happen, and it made a new account. I'll delete it but why has this happened. I then got an email to the same email address saying that the account is now set up. Is this because of the dot in the email address that someone else might have or is something else going on?