[Samba] Password caching issue

[Daniel Jordan]

Hey list,

i've stumbled upon a very strange behaviour.

I change the user password on the pdc with "samba-tool user setpassword ..."
two times in a row, without login in or out anywhere, to make sure the 
password
is only stored on the dcs.
After doin so i am able to login into our webmail interface, which 
authentificates for
testing only against the pdc, with both passwords for about 45 - 60 
minutes. After
that time the login is only possible with the last password set.

Is there any password caching mechanism in Samba which i am not aware 
off? And if
so, is it possible to shorten the time or even disable it at all?

Thanks in advance

Daniel