Bill and I added four budiges to our budgie colony several months ago. Among them was Pope.... a yellow, fearless, energizer bunny of bird that we both loved. Pope and Fedor, our only males in the colony, were best friends. They always played, ate, and preened together... that is, when Pope wasn't causing chaos.
Here is a video of Pope playing (running back and forth... it happens a few seconds in) just days before he died.
http://www.youtube.com/watch?v=2ybEVkA_MGo
Bill and I have no idea how old he was, but he had no symptoms whatsoever. He was playing and trying to escape from the cage hours before he died. We think that he probably had a heart attack, as we found him on the bottom of his cage, upright, and gripping the bars very hard, but we'll never know for sure. All of the other budgies are fine, though Fedor seems a little subdued. That may just be in my head though.