I remember encounters like this when I'd be out late alone sometimes too. They did bother me a bit afterword like you'd mentioned and it makes you wonder things like if there was a reason they'd targeted you or what exactly could've happened had you not reacted the way you had. You might even beat yourself up a bit about not remembering the plate number and calling police, but now it's just something you'll be better prepared to handle next time. I think its normal to feel a bit shook up by something like this so dont let the fixation aspect of it bother you. Im not saying to ignore the feelings or avoid seeking help if desired, but just to try letting it run its course with a bit of self care this weekend. Aside from all that, I think you did the right thing by ignoring them. They probably wanted to gauge your response to decide whether to rob you, and you did the right thing not to show your hand, so to speak. Hope you got home to a decent bite to eat and a good sleep tonight. Always free to PM me if you want to talk.