A careful follow-up shows that the conversation mattered after it ended.

Most talk evaporates on contact with the next thing. Someone tells you about an interview, a scan, a difficult week, and the moment is warm and then gone, which is why a message arriving days later carries more weight than anything said at the time. It shows the subject stayed with you when nothing was prompting it and nobody was watching.

Think of one thing somebody told you recently that had a date attached to it. Send a short message on that date asking how it went, with nothing else in it.