What if you had been mugged by a white person? Would you then carry the same fears moving forward? I have to assume you are not black, and thus, to you, black is "the other". You are making the assumption that because one person was dangerous, everyone else with that skin tone is dangerous. I'm sorry, but that is textbook racism
EDIT: After a second look I realize this is probably what the parent post is trying to get at :-)
It's a bias. Let's assume that all muggers wear red pants (or you have been mugged mostly by people in red pants). So when you see somebody in red pants you cross a street. It's surely not a textbook racism, since no race is involved. Also how do you know that anybody wearing red pants is a mugger? The tragedy of blacks is that they can't change skin color, unlike pants. This bias will exist until crime percentages will at least equalize between blacks and whites (do they?). You can call it a racism if you want but it doesn't change anything. I have worked with many blacks, I had zero problems with any of them, I don't consider them worse than me in any way, but I will cross that street. Sorry. There is a difference between a concrete person and statistics.
Now for jumping to the defensive the moment a man asks you a benign question, because you assume he is sexist because of his gender - isn't that sexism?
EDIT: After a second look I realize this is probably what the parent post is trying to get at :-)