This article strikes me as damage control more than anything. Seems to me, Bush has been photographed many times throughout his career making this gesture. Furthermore, American Jesus freaks have for years sought to sensationalize their attempts to censor popular music by showing rock musicians making the "devil sign." Photographs of the horn-finger salute can be found in many mediaeval depictions of the devil, as well as in photographs of Aleistair Crowley. The sign was first adopted by American musicans like Ronnie James Dio, who achieved fame in the mid-70s as lead vocalist for Rainbow, and Gene Simmons of Kiss for theatrical purposes.
Crowley, it should be noted, was a 33rd Degree "Master" Mason of the Scottish Rite. Many of the ornaments and trappings of the Skull & Bones Society at Yale, of which both George W Bush and his father and uncle Averiel Harriman (who bankrolled Adolf Hitler's steel industry during his military buildup), were members. Among these symbols are the skull and crossed bones (used by the Nazi SS) and ritual coffin, used in the Skull & Bones initiation ceremonies.
Interestingly, for all Bush speaks of "God" and "The Lord," has anybody ever actually heard him cite Jesus Christ as his savior? Isn't that just a little unusual coming from a devout Christrian?