It sure seems innocent enough. Though there are times it's said with a desired effect, the simple phrase "good shot" has many times been followed by a miss. After teaching yourself how to ignore it, take it in context, respond to it, whatever, it can still catch you off guard at times, and you know the rest of the story. Watching tournaments with novice players, the difficulties of inexperience with pressure on full display, the response to comments is remarkable. You could almost bet on a miserable shot coming. Is it lofty expectations for the next shot? Is it managing the self doubt from an unexpected success? Why is this so common? What's the psychology behind it?