Did you lost someone!

[Gaijin]

When I was a child I loved my grandmother more then my mother, probably I still love her more.
A week when she died she was saying good bye to everyone in our family and everyone she loved, but not me, I was not there.......
As soon as I got back a month later, the first night in the same house where she was, I had the most real dream ever in my life.
I heard that someone is getting into a house, so I tried to look who it was and my grandmother was standing in front of me, with the result of my puls getting high as I would power up an a-bomb, adrenaline pumping into the head to clear my fear of what I just saw.
The talk started with me saying, You're dead, you can't be here, and I was flipping out.
My grandma calmed me down and told me, "I'm just came by to say goodbye to you, I've missed you!".
After all the talk, she left the room, and I woke up with a really calm head and a happy feeling for being able to spend some more time with my grandma.

Explanation, please!