I believe you did have an encounter with your grandmother. She wanted you to know she's still connected to you. I was close to my maternal grandmother too. I had a vivid dream about her one night. I wish I could remember more details, but I was flying on her shoulders as she pointed out the scenery in the most beautiful place I could imagine. .Was it some higher astral plane akin to the afterlife? I'd like to think so. Our loved ones never truly leave us. :-)