Yes, this has happened to a few EMO owners with the power going off, EMO will start wandering off, I think even with his feet sensors there isn’t enough time/room for him to react when he is on his skateboard and he could either fall forwards or even backward if he freaks out.
what I’ve done is placed a barrier behind my EMO on my desk, so if the power does go off, they can only fall forward. (see pic here). did test this a while ago, EMO:One fell flat on his face. (R2 tried to help, but he couldn’t do much – EMO:Two just laughed)
As you’ve mentioned, the positioning is important and it’s always recommended to build or have EMO in some sort of play area where cannot fall off the edge of your table when he is playing on his own or with his buddy (if there are two of them), as accidents can always happen also their feet sensors even though they work well, they are never 100% fullproof.
hope your EMO is ok after the fall!