i am seeing the same thing.  i just did 'J s' and am sure all articles are
downloaded but the summary buffer still highlights those as undownloaded.

it didn't happen yesterday.  i am using the latest from cvs.

screen shot attached.

Kai Großjohann writes:

  Kai> Look at this screenshot.  The "-" in the leftmost column means the
  Kai> article isn't downloaded, but Gnus is unplugged, and I can see the
  Kai> message!

  Kai> What's the story?

  Kai> I think this happened only recently.  -- Ambibibentists unite!

-- 
Danny Siu