It's surprising how rough dogs can be when they chew on things that even a healthy tooth can be pulled out. The tooth can be snapped right down at the gum too.

There was never anything wrong with our Monty and Jess even though they lost some incisors due to rough chewing and BCs often aren't even penalized in the show ring for having broken/lost teeth etc...because they are reknowned as chewers etc...

By all means have her checked but I don't think you need to lose any sleep over it. You'll get used to seeing her with the gap even though it might seem a little disappointing to you at first.