This drabble is so sad, and yet so nostalgic too. I adore the mood you set at the beginning with him reminiscing about the times he had with his grandfather when he was little, and the downward spiral you gave the rest of the story.
I love that he truly regrets saying those things to his grandpa, and that he wishes to take the words back. It reminds us that you always need to leave on good words, because you'll never know when it's someone's time to go.
I liked that the ending confirmed that his grandpa had passed, and that you didn't specify on what he passed away of, leaving that to the reader to decipher.
Very well done drabble, and I think I found a typo. xD
he came to tell his grandma that we was going to work on a boat,
The first paragraph is my favorite. It creates the atmosphere :) Also the memory included in it, it made me kinda nostalgic :] And I could imagine the little boy with his head full of dreams, listening to his grandpa's stories...