Did my budgie die of old age?

My budgie, Tweety Bird, died tonight. I know silly name but the wife named him so it is. But he has been sleeping a lot more than usual the last few weeks. He eats fine. We hand feed him seeds and millet on a regular basis. Plus he eats his regular food. This morning he was sitting in the bottom of the cage sleeping. I thought he might be dying but this after noon he was perky and eating as usual. Then tonight he died. He is eight years old. He also just recently was separated from his birdie buddie, Oscar, a love bird. We got Oscar a mate. But they have been in the same cage until tonight. Any ideas out there?