Unless they are intentionally deadbeating (as in there is some evidence that they didn't miss by accident or get called away) on multiple separate occasions there in nothing to report. Recommend FOE and rate accordingly.
If you think it was intentional deadbeating, that is against the rules. But it's hard to tell. Sometimes things like this are noted in case they happen consistently. If you think it may have been intentional deadbeating, you can file a Cheating and Abuse report here