I think the warning only comes up for the first poster to repost. Then there are about 10 further posts from people who don't know it's a zombie.
Some are about the most inane things. I have one about someone extension from over 10 years ago, another about the baby name Guy 
How does that even happen? Someone must have searched for the thread and thought 'oh, there's a thread from 11 years ago, I'll post on that'
I'm not feeling very tolerant this morning.