are you not over reacting to this there could be 1001 different reasons to ask you this question.

Give us 5?

1. she thought i was dressed in a threatening manner

there we go 1000 more to find

Ok then maybe a few reasons. Maybe she has had drive offs. Maybe the cctv wasn't working. Maybe a car similar to yours has been involved in fuel thefts. Maybe she was new at her job, on her own and felt insecure/ frightened.

Whilst I can imagine it was pretty annoying it really isn't the end of the world.

Maybe time to move on and put it behind you. Perhaps when you talk to the manager there will be a rational explanation. Go in with an open mind and be pleasant.

All the best.