Yes it's just shed, no worries. You can gently use your fingernail or even a tissue and lightly pull up around the outer part of his nostril, the exterior shed will lift up, and then (don't be alarmed, it's kind of gross, lol) a long string of shed will actually pull right out of his nostril. It doesn't hurt them at all, actually it has to be relieving, but I remember the first time I did this years ago to a large adult beardie and I was kind of horrified at the long piece of skin that just lifted right out of his nose!