Listening Phone (Maybe)

I have puzzled over how I was ever targeted with certain advertisements. The ultimate riddle occurred last week, when somebody brought out a 32 bass accordion. I said that I had once been offered a 48 bass accordion, if I would learn to play it. Within a day, an advertisement popped up on my computer for a 48 bass accordion (pictured). But how? I only referred to it in that brief conversation, and nowhere else. OBSERVATION: It is possible that a phone was listening in: Does Your Phone Listen to You? "The possibility of technology being used to target customers based on their conversations is concerning ... The anecdotal evidence is quite compelling." It was a Chinese warehouse.