Password Expiration timestamp

Hi

I was pulling a report from AD,  I can see last logon date as month of 7 and Password expiration on month of 6 . Ideally password should have been changed after month of 6 and new expiration date should show month of 9 . IS this any replication issue ?

Last Logon Date           Password Expiration                             Date Password Last Changed
7/18/2013 6:40            6/28/2013 23:43                                 4/29/2013 23:43

I am just new to AD setups . Could you please help here ?