I've heard of it happening now & then. Personally I'm not a fan of 'assist' feeding ever, but I've had great outcomes with the more gentle method of tube-feeding
thinned (w/ a little water) chicken baby food to snakes...no bad outcomes ever, done many times. It's a skill I recommend picking up...sorry for your loss. I think it
probably was not a result of anything you did, but rather occurred in spite of it.