I was on a walk earlier, went about 4 miles with no issues, until towards the end when I heard footsteps behind me, and noticed there was a trashy looking man in his 20s or so about 20 or 30 feet behind me following along at a slightly faster pace than I was making, staring right at me like I was a target and he some sort of predator, with his hood over his head despite the fact it was way too warm to have a hood on. Never stopping walking, I transferred my snack filled grocery bag to my non dominant hand to facilitate drawing, and picked up my pace, turned in 90 degrees to go into a parking lot of a corner building where he kept following me. I then lapped the building until almost going the opposite direction, then stopped, and waited for him to come around the corner of the building, to see if it was just me, or if he was really following me. When he did, he stared at me for a couple seconds, then went in the other direction.
This was not in a particularly dangerous area, but it was earlier in the morning before too many people were about, and I got the impression he wanted to try and catch me by surprise and steal my gun, probably for drug money, if that wasn't already obvious. The fact I had my grocery bag in my draw hand, in his apparently nut case mind, I imagine made him think I'm some foolish yuppie who doesn't understand the way that street fighting works, or some such crap. But as it was, there wasn't even enough to confront him, let alone call the cops, at least until I could verify he was actually stalking me.
It is for me, the first time I believe my armed status almost cost me some trouble from someone other than a cop. Considering the number of times that my OCing has scared off punks, it's a good trade off. But I do find it a great example of why OCing while not knowing what you're doing, or while being apathetic to your surroundings could be a severe mistake.