If you do nothing, then yes. What you need to do is go to the page with the session details. Its status should say "waiting for confirmation". There should also be a "there was a problem" button, which you can use to dispute having to pay for the session. However, you have a week to do all this, so the first thing you should do is send a message to your teacher and ask if things were OK on his/her end. It is possible that something happened and the teacher was unable to come online - time confusion, personal problems, other work commitments, blackouts... I had to deal with frequent blackouts while living in Turkey, so there were a couple of times where I was forced to miss a session. I wrote an apology email once the power was back on, and suggest another time for the lesson. If you're able to rearrange a replacement lesson without re-booking, then I would try doing that first of all.

Another thing to consider is the recent switch to daylight saving time in the US. If your session was supposed to occur Sunday or today, maybe you 'arrived' an hour early in relation to your teacher.