At first I thought my NBcheck charge on my bank statement was a mistake, but then I stopped and thought about where it could've come from. It turns out I had a site membership for $40 that ran for three months (I used my checking account to sign up instead of my credit card). When the three months were up, it auto-renewed for one month at $12.97, which is what the charge was for. I made sure that auto-renew was turned off so it shouldn't be a problem.
If you joined a site in the past and forgot to cancel your membership, that may be where the charge is coming from. Just a thought.