Noticed Screen/display glowing hours after lock in cold weather (-3 F).

Went out to my Bronco a couple hours after parking and locking it and noticed a slight glow in the display. I opened the door then shut it then locked it and the screen went completely dark.

Aside from the potential that it was an update, is this some kind of normal precaution the computer does in really cold weather or am I walking out to a dead battery tomorrow?