Update Jan 02, 2006: I relocated this bird in east Houston six weeks later.
This
gull was at East Beach, Galveston, Texas on November 16, 2005; the default for this type of gull in Texas is thayeri, but the pattern of the mantle/upper scaps and greater secondary coverts look wrong for that taxon, as does the bird's normal posture with tertials fluffed-up, and a small "skirt" of secondaries visible beyond the greater coverts; also the bill base looks too pale for thayeri in November, as does the lack of any light barring at the base of the tail - all the preceeding features would seem to better-fit a smallish (female?) Slaty-backed Gull:
