I think you nailed it. And the SS guy was in plain clothes, giving her more justification for thinking she was in danger.
Why was she in DC? She was from out of town. Was she on vacation or what? Driving around in Washington DC can be confusing if you’ve never been there before. Was she lost? One time I was driving around in DC area as a tourist, and I ended up pulling into the CIA place. The guard was nice. Didn’t shoot me.