Microsoft narrows Win10 upgrade options to 'Upgrade now' or 'Upgrade tonight' | InfoWorld
I suspect this is related to the fact that yesterday Microsoft moved KB3035583 (the GWX app) to Important. Remember to keep your updates on manual and screen for this. If your parents are anything like mine, when you go to Christmas dinner, you might have to revert their system for them.
windows 10 is still a ways from being mainstream ready, probably a good 6-12 months more work is needed before all the problems are cleaned up
what is out now is on par with how vista faired, when 7 shipped it was vista done right
i expect that 10 will be updated lots over the winter