Random Thoughts: Am I the Only One Who Noticed Snape taught Harry his Signature Move?

So, I'm going through one of my annual Harry Potter rereads, and after reading the Chamber of Secrets for the gazillionth time, it hit me. Snape taught Harry "Expelliarmus." The spell that went on to become Harry's "signature" move was introduced to him by a man he loathed.

When I say I've read the books a gazillion times, I'm only sort of exaggerating. Okay, I'm exaggerating a lot, but I really do reread the series at least once a year, usually two or three times, depending on how busy that year is. This is the first time I've made this connection. Maybe I'm a little slow, but whenever I see a post or listicle with Potter facts, I'm all over them, and I can't recall ever coming across anyone saying anything about the Snape - Expelliarmus connection.