I was observing some of the people studying through the viewfinder. I focused on her, attracted by her expression, and recomposed. Just at that point she happened to look my way so I released the shutter.
I was using a 70-200 at 200mm and f2.8, so the BG blur is caused by the lens. I wanted to isolate the subject. I'm not actually reflecting the scene as the eye would see it, but rather it is meant to be "another portrait", with the only difference being that I did not set it up, nor take the time to clean out elements in the foreground or background that I would normally have had it been a posed shot. Notice I mentioned "in my portrait work". I hadn't considered that people looking at the camera cannot be a candid.
So then does a true candid mean the subject looks away from the camera? I hadn't realised that this was a criteria for a candid shot.