Hmm this is not new. I have seen a dozen of websites like this. For example, examine wordpress.com you can see that.
It reads something like this:
"If you're reading this, you should visit automattic.com/jobs and apply to join the fun, mention this header"
I got this when I was sniffing my own network packets while browsing wordpress.com lol I was trying to demonstrate BREACH attack back in summer....