Clock Changes did not take effect in my AH-OS

Not sure if this is important or a bug:

My nightly builds on Anthill OS on a WinXP machine are set to for 3 a.m.  
During this past weekend, the PC clock automatically changed to the new time 
but the build didn't start until 4 a.m.  So this part makes sense.  Well 
kinda!

But if most PC clocks or computers are set to change around 1 or 2 a.m.  I'm 
baffled as to what happened?  It doesn't make sense.  Should a clock change 
require a PC reboot?  Or Anthill kept track of time by caching it, based on 
the old time?

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