What happened in the middle of the twentieth century that will not happen again for 4,000 years?

Question

A girl was standing near the window thinking something. All of a sudden she decides something and throws something out of the window. She dies very soon after throwing it. She was perfectly healthy and had no disease or allergy. No one killed her and she did not commit suicide.

Can you think of any possible explanation that is logical as well for what happened there?

Answer 1

A year like 1961, which reads the same up-side-down. This will not happen again until 6009.