Detail I Noticed to think about

I was re-watching the end of evangelion, and I had made it to the final scene with Shinji and Asuka on the beach and i noticed something

On the makeshift tombstone Shinji erected that misatos cross hangs from, it seems to have rusted over somewhat. Implying that between the third impact and when instrumentality became a choice there is as a long stretch of time, could’ve been weeks, months ,years ,decades, centuries and we wouldn’t know.