[Samba] PAM validation ...

Thu Dec 22 20:30:54 UTC 2016

please, oh please, why do the machine acounts fail:

[2016/12/22 21:06:48.172161,  0]
../source3/auth/pampass.c:797(smb_pam_accountcheck)
  smb_pam_accountcheck: PAM: Account Validation Failed - Rejecting User
xyz-pc$!

pdbedit -L for that machine account shows that the password changed some
days ago:

Password last set:    Mon, 19 Dez 2016 14:11:20 CET

As I didn't do a thing ... who or what?
And how to solve that?