Thankfully, the sentiment wasn't lost on Roald Dahl. His lovely response can be seen below.
Transcript follows. Image kindly supplied by the letter's recipient, Amy, who can be found on Twitter. Many thanks, Amy!

Image: Amy
Transcript
GIPSY HOUSE
GREAT MISSENDEN
BUCKINGHAMSHIRE
HP16 0BP
10th February 1989
Dear Amy,
I must write a special letter and thank you for the dream in the bottle. You are the first person in the world who has sent me one of these and it intrigued me very much. I also liked the dream. Tonight I shall go down to the village and blow it through the bedroom window of some sleeping child and see if it works.
With love from,
(Signed)
Roald Dahl