Yes there is a reason for it and no, it has never been removed.
It's just a warning, it's not a problem.
It comes up when you run two instances of LFS. If that's what you wanted, ignore the message. It's useful for people who start two copies of LFS by mistake. For example (1) they already had one opened but it's minimised or (2) they launched it twice by mistake.
This is not a bug! :spin: