Holy crap. Am I really so jaded that when someone knocks on my door without prior notice, I get a burst of adrenaline as my first instinct is home invasion?
No, it's my across-the-hall neighbor looking for a screwdriver (which I don't have). And really, self, would a home invader knock first? Only if they're quite polite, I'm sure.
It's finals. That's what I'm blaming everything on. Final finals. Finally.