samba - Mar 2009 - Error: Rejecting auth request from client MAILBKP1 machine account MAILBKP1$

I have a Samba 3.3.2 member server, named mailbkp1, which I joined to a
Samba 3.3.2 domain controller.

At joining time, I got two errors on the domain controller, which I
report here:

[2009/03/31 14:08:47,  0]
rpc_server/srv_netlog_nt.c:_netr_ServerAuthenticate2(546)
  _netr_ServerAuthenticate2: netlogon_creds_server_check failed.
Rejecting auth request from client MAILBKP1 machine account MAILBKP1$	

After joining, users can logon properly, and everything seems to work,
but every time the member server gets a new connection, and contacts the
DC to authenticate the user, I get that error again. 


I have searched through the bug tracking system, and found that older
versions of Samba showed this behaviour, but I supposed that this was
corrected on later versions.


I have also tried joining a 3.3.2 Samba server to a NT4 PDC, and while
the Samba member server works properly, I get similar messages (the
machine failed to authenticate itself) in the Event Viewer of the NT4
PDC.


Is there an open bug abut this? I have found none.