Yeah this happens a lot. You're exactly right, primitive clients (like the one I use) don't even show follower count or "trusted connections" 2 things would be, I either added it to my list a few years ago, and/or followed based on someone else repost. The other issue is this usually when resolving @ mentions, actually selecting the right npub. I don't remember many public keys, just the ones I have to juggle regularly. " off to see how many odells I follow XD