No. 89-1719. Argued September 19, 1990. Decided September 13, 1991. Frank S. Manitzas, San Antonio, Tex., for petitioner. Karen L. Arndt, Atty., N.L.R.B., with whom Paul J. Spielberg, Deputy Asst. Gen. Counsel, Aileen A. Armstrong, Deputy Associate Gen. Counsel, Washington, D.C., were on the brief for respondent. Petition for Review of an Order of the National Labor Relations Board. Before BUCKLEY, WILLIAMS and D.H. GINSBURG, Circuit Judges. Opinion for the Court filed by Circuit Judge D.H. GINSBURG