Personally, I wouldn't bother going to my vet for something so minor, unless it continues to get worse, or the dog is showing worrisome behaviours like constantly scratching the area.
Many dogs like to dig a hole to bury things. They then use their noses to cover the thing over, and this results in the nose getting some of the hair worn off.
It could also be insect bites. Because a dog doesn't have much hair on that part of the nose, it's a great place for insects to bite.
There are a number of things that could have caused this, and none of them mean your dog is sick. I'd just keep an eye on it for now.
Now, if your dog has mucus coming out of its nose, that would be a different story. Just like with a human, that means he IS sick, or has something stuck in his nose, and needs to see a vet.
There is a potential for fungal infection, bites, bacterial sores, scrapes, even allergies to grass or brush.- all sorts of things on that area of muzzle because of the nature of GSD to be scent driven. Often you will find a young GSD with a raw strip across that area from running it through the grass in your yard. To me, they appear to be small pustules. If the small sores spread it is enough to seek treatment. However, if you haven't heard before - do not use tea tree oil on your dog. There are several common thing that humans might do but are toxic to dogs and that is one.
Bottom line is you have to be comfortable with what is going on and if you are not - check with a vet (which I am not) to make sure it's OK. Most of us would take a "wait and see" approach to that.