That's awesome! I had a somewhat similar experience (shared previously [0]):
> I proved a topology theorem in a dream once.
> Before I went to sleep, my inability to prove it had been bugging me all day long, and I suspected it'd be featured on the next morning's (way too early) final exam for my university course. I solved it in my dream, woke up, wrote on my whiteboard what I remembered and sure enough, it was correct. I worked it a few more times to cram it into my memory before running to my exam.
> To my great delight, the ability to prove that theorem was featured heavily in one of the exam's questions, and helped me do quite well on the exam overall.