It happened to me. I drank without knowing.
Have been offered an NA beer at a friends birthday party yesterday. For some reason, went in blind just taking my drunk friends word for it. Had about half and it felt off.
When I noticed it was really a mix of emotions. I was angry at myself and my friend. I felt like I failed something and at the same time felt like I knew I defeated alcohol. I kind of wanted to storm off but I stayed.
I am not sure I felt it. I wont reset my counter because it only cimented my desire not to drink. But I am really happy I learned that a couple sips would not bring me back neck deep.