I recently had a dream of Cuba too...and it also had a bus...weird!

You weren't close to becoming lucid, you WERE lucid! You got it, but then you lost it. It's nothing to worry about, just a few things to keep in mind for next time is to use a technique to increase clarity right when you become lucid. Here are some things you can try:

-Rubbing your hand together
-Spinning
-Yelling something like CLARITY or VIVIDNESS
-Stopping and reassuring yourself that you're in a dream, not rushing into things

Better luck with your next LD!