Strange happening with 'git fetch'

This is very strange, and defies the understanding of everyone in the
office familiar with git.  Is it a bug, or some feature we don't
understand?

Basically, when I do a 'git fetch', it updates my local repository.
Now nobody else is doing anything, so the remote repository does not
change.  Doing another 'git fetch' should report that nothing needs to
be done and nothing should change.  But instead, it reports something
about the remote HEAD, and changes my local branch 'master' to some
strange location!  Running 'git fetch' again restores it to the
correct state, reporting that it is updating 'master'.  Repeated
invocations will toggle between these two results.  Below is a
transcript from the bash shell.

Can someone please explain this?

---- bash console ----
dkirk@RI-ENG-21 /c/Dev/TSWeb2 (master)
$ git fetch
From //10.18.0.53/git/repos/WebTrading
 + 03c60a4...209b0bc HEAD       -> origin/HEAD  (forced update)

dkirk@RI-ENG-21 /c/Dev/TSWeb2 (master)
$ git fetch
From //10.18.0.53/git/repos/WebTrading
 + 209b0bc...03c60a4 master     -> origin/master  (forced update)

dkirk@RI-ENG-21 /c/Dev/TSWeb2 (master)
$ git fetch
From //10.18.0.53/git/repos/WebTrading
 + 03c60a4...209b0bc HEAD       -> origin/HEAD  (forced update)

dkirk@RI-ENG-21 /c/Dev/TSWeb2 (master)
$ git fetch
From //10.18.0.53/git/repos/WebTrading
 + 209b0bc...03c60a4 master     -> origin/master  (forced update)

Thanks,
-David