@julian thanks, i got it~
How psychobunny visits the site or 'about a month ago'
Last Online - about a month ago.
But it was only recently.
I saw it with my own eyes.
It is not so important, but it is interesting the phenomenon.
It's because I "appear offline" as my user setting.
If you think about it, it makes sense, because if I am appearing offline you can check to see if I'm actually online by looking at the "last online" (which would say "1 minute ago")
That said, I think that "last online" should be updated when the user does something public such as reply to a post