1. You guests should have received an email to review you. The reminder to review should also be in their messages under notifications.
2. At times airbnb is not prompt sending the email to review. Wait a day or two and it should show up in your email.
3. Sometimes the guest cancels because they put in the wrong dates or wrong # of people. My guess is (and I've had this happen) is that they canceled for some reason and then resent their request. This could have happened very quickly (OMG I put in the wrong dates--quick cancel) It shows up as a cancel reguardless of who did it.