It’s always a bit strange when you only hear from people once every few years, just as they need an intro or career advice or whatever- the beginning of those conversations is usually a bit of sheepish catch-up on what happened after you last spoke with them. Similarly, there have been times when I have felt like a dope after realizing that I failed to follow up myself after a call, and am again reaching out for another reason.
However, when you follow up with someone as simple as “Thanks for connecting me with so and so, we had a great chat” or “I tried that thing you suggested, here’s how it worked out”, you build mutual trust and enthusiasm for a successful outcome to the conversation you had. It’s a genuine and thoughtful way to grow your relationship.