I have done some deep diving into the code.
Have run a diff over the old code (24.0.12) vs the new code (25.0.6) and have not found anything that looks changed around the Expiration date gathering/comparisons area.
I am thinking that the setting of the Hour,Min,Sec to 0’s and New Zealand being in Standard Time at the moment UTC+1200 that when the comparison comes along its tripping over this.
As an experiment (and have to wait until tomorrow morning to test) I have the ability to change a test system to Australia/Sydney time zone to see if that makes a difference.
JP007