ms.spiritseeker, that is one of those kinds of encounters that is so strongly felt, I refer to them as a soul-jarring experience. The same happens with some dreams that seem to jolt you so hard, when you awaken, you feel like your consciousness has been on the wildest ride at the carnival, and you feel like you need to kind of shake your head to clear it and allow reality to settle back in. It is not uncommon for children to encounter ghosts, and it is sad when they tell an adult, they are told that they didn't see that person, because they don't believe that person's ghost was there at all, and it was explained by some other method that they are more familiar with or more comfortable with. Maybe it is because they don't want the child to believe in ghosts, for fear of scaring them. Who knows? But, if you experienced it as a child, you know in your heart of hearts that it was real. It is great that your grandfather came back to visit you. He probably was just checking on you, to make sure you were OK. If you haven't seen him since then, perhaps he just wanted to say goodbye to you.
My husband's mother passed away when he was 7 years old. She had leukemia, and died young, leaving 3 children and a husband behind. My husband was the youngest of the three. A few days later, he saw her standing at the foot of his bed, He doesn't recall exactly what she said, but she was evidently checking up on her "baby", to make sure he was alright. We still own the cedar bed that he was sleeping in at the time, and that happened nearly 70 years ago.
It is great to hear how people come to be interested in and to believe in ghosts.
Mare