It looks like some irritation of the nose there. I would recommend monitoring this for now to see if it resolves on its own, especially if Shadow does not seem bothered by it. Any kind of mild allergic reaction to a bug bite or substance can cause lesions like this on the nose; therefore, it is perfectly logical to wait and see if it improves with time. However, if the redness seems to worsen, spread or causes Shadow severe discomfort, then its best to have your vet take a look at this. Some other possible causes for this would be a severe allergic reaction, inflammatory response to a foreign material or substance, or even a possible autoimmune skin disease. Further testing would be needed to help find out the underlying cause if things don't improve.
I hope that things improve with Shadow and his red nose. Best of luck moving forward. Take care.