I hadn't noticed this until someone else brought it up, but same here. 4.5 year old Zephr model used to shut off almost instantly but now I can hear the fans spinning for a good 20 seconds after the green power light turns off. It's definitely from the update.
Is cloud-sync enabled? This should be the reason.
And 3 red-lights only means: Problems with power-supply. There can be many reasons