Random Apple Watch question

Does anyone know if an Apple Watch has to be paired to your phone to use your Apple ID. I got a random notification that an Apple Watch was using my Apple ID but my phone was powered off. I did check when I turned it on and it was able to make calls on it. So I don’t know if it was an old delayed message from yesterday or what? Any insight? Lol

Also my devices on Apple ID website show just my phone connected as I changed my password and disconnected other devices but now I’m paranoid my phone has been used for someone else’s watch. Somehow.

Just to clarify. Wondering if only one watch can be paired at a time to a phone and if it has to be paired to that phone to use that Apple

ID? Lol