Hail can damage your roof without any visible signs from the ground. Hail normally has to be the size of a golf ball before it will break through your roof or cause bruising. Sometimes these damages do not show up quickly or are easily overlooked. The integrity of the shingle may be damaged, do not take a chance on it. If hail is driven by high winds or if it lasts longer than a few minutes, even small-sized hail can cause your roof to suffer severe damage and the loss of their protective granules, which will GREATLY reduce the life of your roof. Loss of granule layers on the shingle can cause the glass based center of the shingles to be exposed to the suns UV rays. This will cause SERIOUS deterioration of the shingle in a short period of time. Have it inspected, just to be safe.