Hey arwings. If you ever go back down that way (or anywhere else you can buy Cubans but risk running into fakes), here's a good idea.
If you haven't already, go to Cigar Aficionado's website, and go to the Counterfeit Galler (its at the bottom of the navigation bar on the left side, its a picture of a Cohiba band under a magnifying glass).
First, look through the galleries, comparing the fake to the legitimate thing, just to familiarize yourself with common fakes.
Then, if you have a good color printer or your office/local library does, make a page in Word or Paint or some other program with all the pictures of the legit bands on it, and print it out for your next vacation, that way you can compare bands to the real things.
Of course, you can still run into counterfeits, but that's one way to help. Also, if you decide to buy a box, do like Slim said, only buy from a place that is a registered "Case del Habanos" (spelling?), displays the official Habanos SA license in the window, etc., and make sure the box you buy is closed and the Cuban tax stamp is intact (you might also want to print off a pic of the new Cuban tax stamp, to make sure all the water marks, special stuff, etc is on and it isn't just a fake too).