Originally Posted by Cyclops
Well, could she have been impacted on the substrate?
I doubt that, my snakes regularly drag they mouse across half the enclosure and eat it. Only impaction you should worry about is hard and big (as in big compared to the snake) pieces of bark/cypress mulch or the likes. Finer substrates, small pieces of wood, sand, etc, will pass just fine in healthy snakes.
Can't really say why a snake dies unless it's blatantly obvious. Reptiles generally get unwell/sick over a longer period of time. They are masters in hiding their decease up to the point it will kill them.. Simply check how you kept your snake and ensure it was kept well at all times. You can't really do much more except asking a necropsy from a vet. 1.5 year old snake should eat a lot larger prey than a pinky though. If your snake after 1.5 year was so small it couldn't handle anything bigger, he/she might of had an issue from birth... It happens unfortunately