I'm sure he lived a good life and was treated very well, and that's the most important thing.
Saddest part about our animal companions is that they do live much shorter lives, so we often have to say goodbye far too many times to our beloved friends. I know I've seen my fair share of pets go, and it's never easy, but as long as you remember the good times you had it's all good.
I'll send a prayer out for Lighting, may he rest in peace.