Even this claim has been called into question.

From NY Times: Did American Missile Defense Fail in Saudi Arabia?

Governments have overstated the effectiveness of missile defenses in the past, including against Scuds. During the first Gulf War, the United States claimed a near-perfect record in shooting down Iraqi variants of the Scud. Subsequent analyses found that nearly all the interceptions had failed.

And going into the second linked article:

The United States Army has said that its Patriots intercepted about 40 percent of the Scud missiles that Iraq fired at Israel during the war in 1991. That is a far more modest estimate than the one originally given by the military and by the Bush Administration. In the gulf war, former President George Bush once said that the Patriot's record was nearly perfect.

But Moshe Arens, who was Israel's Defense Minister in the gulf war; Gen. Dan Shomron, who was chief of staff of the Israel Defense Force during the war, and Haim Asa, a member of an Israeli technical team that worked with the Patriot missile during the war, say that one or possibly none of the Scuds was intercepted by the Patriots. They appeared in a documentary scheduled to be aired today on Israel television. An advance copy of interviews with the three was made available to The New York Times.

What had likely happened was that the Patriots intercepted the discarded missile body after it had been separated from the warhead at the terminal phase:

Check out the NY Times article I linked above.