That's interesting! I actually read up on this before, and I think like in your situation, cats can often sense when they are going to die soon, and will hide from their owners because they prefer to pass in solitude - it's part of their nature, but I forgot why, you could try googling to see more details. But the difference here in my case was that my cat didn't disappear or act strange the few days before it died, and I had no reason to suddenly become upset.