Not sure why it just started b/c I haven't changed any visual/graphic settings, either in the game or on my system. Any ideas what's causing this and how to fix?

There are a lot of bugs w/ http://fallout.wikia.com/wiki/Pip-Boy_3000#Bugs

Usually I can toggle the light on/off and/or move a little bit then reactivate the pip-boy to fix this.