Aha! Well, then. That makes perfect sense. +1 for XenForo code (and coders! Go Mike and Kier!) to be able to determine whether someone actually wants to receive the notification or not and execute the code (or not) based on that determination. So logical!
GofD, I just got an email notification of your reply, and I was going to log in and reply but figured it would come across too stalkerish, being so soon afterward, so I'm not going to do it after all.