I listened to a podcast which mentioned a relatively obscure topic in passing using the basic samsung music app on my phone which didn't have a SIM card in, location turned on or an internet connection.

Later that day I see an advert for said obscure topic served on a web page.

Is it possible that there is someone transcribing podcasts or at least scraping databases of their RSS feeds and somehow my music player app is broadcasting that I've listened to a particular file(after receiving an internet connection)? The alternative is that the machines really are listening.