It's very unlikely that you were actually spied on by A.I. in this case. Think about it this way.

You probably see at least 20 ads per day which gives you 7300 different ads per year. You probably talk about at least 5 distinct topics per day which gives you at least 1825 topics you talk about on yearly basis. It means that for the calendar year there are 7300 changes to hit just one of those 1825 different topics at the right time. It might sound like quite the unlikely coincidence, but it's actually fairly likely for it to happen to us at least once a year given this situation.

It's like the Birthday Paradox, we are pretty bad at estimating the correct chances of something seemingly unlikely actually happening. (I hope you don't mind me linking to a 3 weeks old post of mine here).