He listened and engaged, but said, look, send me an email, I read every email I get. Cool to see that play out with a positive outcome for this guy.
Should just say "I will email you about it".
And actually to be even less annoying might even want to skip saying anything when you meet in person. (Unless of course you are somewhere where it's expected and appropriate).
Just send the email and say you saw him and didn't want to bother him. Or actually don't even say that. Why make it seem like you weren't motivated until you saw him either in person or on TV. [1]
[1] I did two deals with someone who is on a reality TV show. I didn't even mention that I watched the show. I just went right into the pitch (which worked). Everyone is different but that is what has worked for me (on several occasions) in the past.