I am so sorry for your loss. I doubt it had anything to do with your cleaning of the tank. I normally spritz my tanks down with Clorox Clean-up, then rinse with water and dry thoroughly. None of my snakes have ever gotten sick from it, and for some reason my male goes out of his way to lick the glass every time I clean the tank. (I have to make sure I rinse his VERY well.) But no, I don't think you did anything wrong. Perhaps he had an internal parasite?

Again, I'm so very sorry for your loss. I lost my first snake a little over a year ago, and to be honest, I'm still not completely over it. Contact the breeder for sure and ask if he/she has had any other snakes get sick lately. Maybe that could shed some light on it. At the very least, it will let them know to be on the lookout for anything out of the ordinary.