I was just going to mention “Smile Driver”, as I started to read your post! Sounds like the same guy, although I don’t recall him having the bubbles.
I think all of my encounters with “Smile Driver” on the 128,(fewer than 5, I believe) were last year. My first encounter with him was around 15 months ago, IIRC, and I got on his bus to head down to Thriftway. I’d had a rather bad morning, after reading something on a website, and was pretty down. As soon as I saw the sign in the front window of his coach, (as well as at least two others on board, I think) I genuinely smiled and it brought me out of my funk.
I made sure to let him know that when I got off the bus! :-)
Mike