Yeah, I get them all the time too. It started happening immediately after I joined the GCN club in Strava, which currently has over 60k members from around the world. I think it's from people who see my ride show up when they view the club activity feed. I typically click on the user's name and check out their profile. They often have photos and such from their own rides, and it's kind of fun to see what the area they live in looks like, especially when it's a mountain biker on some trail or whatever.