From another dandelion brain - this very thing happened to me today. I imagined a poem last night, whole cloth — a lovely thing that wasn’t the least bit tainted by all this toxic election crap. I thought, “it’s short, I’ll remember, it will be great” — this morning it’s gone. I can’t remember one blasted word of it, or even a theme.
Hence my tag line, “Write it down!” I must take my own advice.