Yeah, he went back in IIRC 2015 and added bonus panels to all of the old comics. He also added alt text to some of the old comics starting with the first, but then stopped for some reason, and then started again. At https://www.smbc-comics.com/comic/2004-04-08, they just become the date, at https://www.smbc-comics.com/comic/your-dreams he switches to titles instead of dates, with the alt text loosely following that, until he starts adding real alt text at https://www.smbc-comics.com/comic/heaven