i know what you mean about not knowing if you had a lucid or dreamt it because it happened to me the other night but as Jared Boz said as long as you had a degree of awareness it was a lucid dream.

As far as the banana thing goes i think that it was placebo, i used to eat a certain pack of crisps before bed and i would nearly always become lucid because i expected i would become lucid if i eat them. Perhaps you could eat another one tonight and see if you get another lucid, placebo can be very effective.