It could be many thing, including hair that was cut when you skinned it. I also use Saftee Acid and Mckenzies tan. Keep in mind that deer hair is hollow and real brittle. It won't take much abuse from children before the hair starts to break off. It's good that you have the attitude you do, taxidermy and working with fur will humble you until you get the hang of it. The salt you used isn't the best but it will work, the yellow stuff is iodine ( I believe), but salt is used to draw the moisture out. And for a rug type it will be softer if you oil it and break it. Did you get the kit with the video? Breaking it will be the biggest pain, at least to get it soft. I have people call me about doing deer rugs and when I tell them $125, they are shocked. I did a beaver once and the work that went into that one was enough to teach me that I will send them to a tannery from now on.