Well, it sounds to me as if it was a fluke just because its highly unlikely that you would be able to have such a complicated dream without being in REM sleep, but this does relate to a new technique I came up with a few hours ago.
Its called ODILD
Oxygen Deprivation Induced Lucid Dream
So this is how it relates- I wanted a technique that gives a high chance of lucid dreaming without waking up in the middle on the night because thats all a little hit and miss. The idea was to push out all the air from your lungs and not breathe at all until you get knocked out. And then a little bit like WILD your mind stays awake whilst your body falls asleep and you enter a lucid dream. Yes I know there's a load of problems with this technique such as risk of lack of oxygen to the brain resulting in mental illness, but your post made me realise if you could remove the risk of mental illness then this could be possible due to your experiences with dreaming before REM. Sorry for the long post . Thanks!