No, you had a lucid dream because you realized you were dreaming. The paralyzation was most likely because of sleep paralysis. In case you don't already know, it's just your body becoming paralyzed during the dream state or REM to keep you from acting out your dream in reality. Yes it can be a scary thing and it sounds as if yours was just intertwined into your dream. I become aware of my sleep paralysis often and if not for this I wouldn't even become lucid in the first place. Also sometimes, I'll be right in the middle of a lucid and suddenly everything will go black and I'll feel paralyzed all over. I used to imagine monsters were sitting there trying to get me, but ever since I lost fear of it I never really imagine those things anymore. I automatically know what it is so all the hallucinations and weird sounds and feelings just don't phase me now. As for the other question, yes, I have trouble with SP thru out my lucid dreams. It's always disrupting them and causing blackouts. Then I have to just seperate my dream body by rolling out of my real and paralyzed body and that's when I get my lucidity back.