How to Track down why gmane is asking for authentication suddenly

[Harry]

Running Debian 'testing'
Emacs-24 - gnus (1wk since last git pull), so magnus.

I may have posted to the wrong place about this on gmane.discuss.  Here is
probably more likely to get results.

Yesterday I was piddling around trying to make gnus download some specfic
nntp messages from a few wks ago.

I once used the agent extensively but over the yrs have migrated away from
that, from having a huge inventory of messages on local disk, although it
can be very usefull at times.  Gmane has made it unnecessary (Thank you
Lars, Thank you gmane and gnus developers)

Anyway, cutting to the chase... I've forgotten virtually ALL I knew about
using the agent... just tried marking with '%' and trying `J j' or `J s' to
get them.

It didn't work, but this morning I'm suddenly being hit with authentication
prompts from gmane server 'news.gmane.org'  Asking me for my User name. 
when of course I don't have one and should not need one.

Just ignoring the message and pressing <enter> seems to launch gnus into a
massive read of all my `read' messages which would number thousands and
thousands.

In the nntp buffer I see a massive list of messages listed out by number....
I killed after a few minutes.

Can anyone help me track this down?