I've spent some time thinking about this, and the best answer I can give is that I spend enough time thinking about the origins and motivations of my own behavior that, if it's something I might conceivably do right now, or (more importantly) at some point in the past, I can offer up a possible motivation behind it.

Apparently this is becoming more and more subconscious, as it took quite a bit of thinking before I realized that that's what I had done.