"match_group: userid@my.domain not member of mygroup" messages?

I have mod_auth_vas 3.3.0.107 installed as a module for Apache 2.0.59, which I'm using to authenticate web users.  The Apache configuration is as follows:

<LocationMatch "/private/.*">
  AuthType VAS
  AuthName "Private Area"
  AuthVasUseBasic on
  AuthVasUseNegotiate off
  AuthLDAPAuthoritative off
  AuthVasAuthoritative off
  AuthAuthoritative on
  AuthGroupFile /etc/httpd/private_acl
  require group Private
</LocationMatch>

/etc/httpd/private_acl contains entries like the follow:
  Private: userid

This works fine, but I'm getting a bunch of messages in the Apache error_log file like:
[Mon Mar 26 11:00:00 2007] [notice] [client 10.20.30.40] match_group: userid@my.domain not member of Private, referrer: http://www.my.domain/private/index.html

If I remove the entry for "userid" from the AuthGroupFile the user will get a "401 Authentication Required" error - as it should.  Adding an entry for "userid@my.domain" as well as "userid" doesn't suppress the messages.  The same configuration worked fine, without the messages, using the mod_auth_vas 2.x authenticator.

Is there some way to stop these messages being generated?