There is no way to figure them out. I would venture to say that he knew someone would tell you he had been there and brought the ow. He is most likely trying to get a reaction out of you.
When in replay, they have a tendency to go to places that are familiar to them, i.e., places where they use to go w/us and he wants to share that memory with the ow for now. They tend to go on vacations and visit the places we visited w/them, participate in activities that we use to share w/them, etc. It's all part of his journey.
For now, I wouldn't put too much stock into what he is doing. The only thing I would caution you about is...do not react to this recent activity. He got what he wanted...someone told you about the visit. Just let it go. Keep the focus on you.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
