Yes, any state where you are in an altered state of consciousness is a trance.
Sound like you were going through the theta gamma state and falling asleep, which is the blacked out parts. Just practice staying on the edge of sleep, no falling asleep but not waking up fully either. To help you hold on to it, look at your hand for a few seconds, then back at the scene. Keep your attention moving, that helps too.
Michael Raduga called this state “The Phase” and has a handy graph to picture it by, which I posted here: