When you brush your teeth and see a little bit of red on your toothbrush, you might think that it's kind of normal or no big deal. But, if you are seeing any kind of blood on your toothbrush that isn't normal and it is a big deal. It can be a sign that you have gingivitis, which can be a serious problem. Gingivitis Gingivitis is gum disease. One of the biggest signs that you have it is the fact that you are seeing blood when you are brushing your teeth and that your gums are swollen and inflamed after brushing.