AHA! Well, duh, I should have figured that out. There was an extra event, I just didn't connect the two.
It was the first time I'd seen this event, too. A few of my villagers departed by boat to look for the south side of the island. No doubt I'll never find out what happened to them..
I'm sure that event could have a major effect on a small village, but mine had a population of 105, so all it did was make room for a few new babies.
Thanks, laurence.