It looks very strange, but I'm sure if you're worried about your safety, it shouldn't have happened. You should make sure that no one has access to your computer or connected remotely. And also make sure your secret phrase wasn't stolen. Don't store your passwords and keys in cloud storage and text files on your desktop.
To much engagement into online will sometimes leading for hackers to track our activities especially when visiting unsecured sites. It may also some reason which do sharing of computers to the others and leaving you account seen from them.
Not just quite good for us, better to used single computer rather than of visiting internet coffee or what ever where internet connections and IP's have shared for anyone inside.