I'm so sorry, rockonn. But don't feel guilty or alarmed because you haven't yet registered any grief. I've been through the same thing myself. My great-uncle died about five years ago, and when I was told, I was shocked by the fact that I felt no emotion whatsoever regarding his death. It wasn't until the funeral that I felt a real sense of grief at the loss. In a way, the fact that you're upset by your lack of emotion at your grandfather's death is indicative of how much you really cared about him. Don't go beating yourself up over this, man. Just be natural and go with your feelings - your mind will tell you when it is time to mourn him.
Thanks for sharing it with us, my friend. :)