Update: February 27, 2008: more photos of this individual from almost three weeks later - added at the bottom:
This first-cycle gull was photographed February 07, 2008 in the Coastal Plain near Houston, Texas; I do not think it is an LBBG, and although in some ways it suggests YLGU, I feel it most reminiscent of heuglini:-
Update: February 27, 2008: note the active molt of the wing coverts:
Note that the outermost retrices have no dark barring: