Steps to replicate the issue (include links if applicable):
What happens?:
Nothing, at least not anything notification-related
What should have happened instead?:
I should have gotten a notification
I understand that the notification system requires certain things to trigger a ping, and this didn't meet that, but taking a look at the big picture, it should have. This is a common pattern. Somebody pings another user and does something wrong, perhaps forgetting to sign the post. So they go and fix what they did wrong (i.e., in the common case, add a signature), but since the mention of the target user name and your signature didn't all happen in the same edit, no notification is sent. Another common scenario is mis-spelling the target's username and then going back to fix it, but just fixing it isn't good enough, you have to also re-sign at the same time. In the example given here, Gog left off a curly bracket and went back to add it. It looks like he also updated the time in the signature, but apparently that wasn't enough to trigger the notification.
All of these things violate the principle of least astonishment. You end up with something which is syntactically correct but because it didn't all happen in a single edit, it doesn't work. The system really should be more accommodating of realistic human behavior and not require such a high level of perfection.