i agree with polypterus on this one. he and i have discussed these hybrids in great depth, and have both kept the main hybrid which was moving through the trade a few years ago, which is the alligator x shortnose hybrid, commonly referred to as the crocodile gar. i also have a gar which is definitely an alligator x Florida (or spotted) hybrid, of which i have not seen another individual anywhere...which could mean it's a wild hybrid, but it's difficult to know for certain.
anyway, getting back to the fish in question; as polypterus said, the fish pictured does not match up with what i have seen of the juvenile stages of either crocodile gar type (i've kept both types when they were just a few inches long), and looks at this point to be a Lepisosteus genus gar. time will tell, but at this point i would say it's doubtful that it's a hybrid.
either way, it's a nice looking fish, so congrats on the pick up!--
--solomon