Hey Rookie, it could have been hypnogogic imagery (HI), which can occur during the transition from awake to sleep and dreaming. I have on occasion had really vivid dreams while I could still feel myself lying in my bed, just minutes after falling asleep, and just prior to a lucid dream. These transitional dreams/images are in a lighter stage of sleep, and could be what you experienced, since you said if someone had even called your name, you would have awoken.

And like melanie said, sleep paralysis isn't the most consistent thing, and also differs from person to person. I don't usually have SP during my HI stage.