Phantom smell or something else?

I was studying and not even thinking about anyone or anything besides what I was studying and out of the blue my ex came to mind, like absolutely sooo randomly and then I got a scent of his cologne for like a few seconds, and I was like what the fuck, like I was in my room, nobody around for me to have smelt that same cologne and I don’t have his cologne or anything which made it even more bizarre. Mind you, I always think about him everyday but I’ve never smelt him like this before. And also, I haven’t seen or smelt him in 3 years. First time this has ever happened to me. I still don’t know what it was…. I heard about phantom smell being a thing and that people smell their relatives that have passed away, but he’s very much alive! What do you all think it might have been?