Congratulations on the new addition... beautiful! I’ve been tempted by the chondros, but have elected to stick with those species I know best....for now anyway.
Over the years I’ve also lost a couple of snakes for no apparent cause, the first to come to mind is a juvenile Solomon Island ground boa that I’d had for a year. They can be difficult snakes to start from neonates, but after a year I felt this one was doing well, consistently eating, etc. I came home from work to find she had died during the day...no symptoms, nothing out of the ordinary, kept exactly like my others. The other unexpected death was my female snow corn. She was an adult when I got her, so I had no history for her or age..a friend got the pair as rescues and gave them to me. In the years I had her, I successfully bred her once, but otherwise she was just a pet. In both cases, I know my husbandry was correct for each species - especially since I had others of the same species that were thriving. That didn’t stop me from second guessing and trying to figure out if it could have been prevented. As others have said, sometimes it just happens and we don’t know why.