I blew my nose in sleep 18 hrs after Septoplasty, right side burns, did I damage graft?

Moving nasal packing inside the nose before it is supposed to come out can scratch the inside of the nose and cause irritation. This may be why the nose feels like it is burning on the inside. The packing is also in the nose to hold the edges of mucosa together so they can heal. Moving them too early can effect the shape of the mucosa that is healing. You probably did no damage but you may want to call your surgeon and see if he wants to see your early. I would expect my patients to call me if they had a concern like this.