ONE OF THE MOST startling results in last November's elections, at least to people who watch this particular race, was the defeat of Guam's nonvoting delegate to Congress, Antonio Borja Won Pat. Mr. Won Pat had been the only holder of this office since it was created, and had risen in the House to become chairman of the insular affairs subcommittee, which has jurisdiction over much legislation of interest to Guamanians. He had been elected before by large margins, and so it was a surprise to almost everyone when he lost.

Or did he? Guam may be the place, as the territory's delegates to past party conventions have been eager to inform television viewers, "where America's day begins," but at a critical moment on election day last fall the lights went out. According to Mr. Won Pat's attorney, the electricity failed at one place on the island -- Guam's election headquarters, where the votes were being counted -- just after a radio station predicted a narrow victory for the incumbent. Then, presto, after the lights went on, the counters declared that Mr. Won Pat had lost by 323 votes out of some 31,000 cast. Subsequent counts changed the numbers slightly, but in each the margin was similar.

The winner was Republican Ben Blaz, who has represented Guam in the House for five months now and was chosen head of the small Republican freshman class. Mr. Blaz's lawyer understandably dismisses the Won Pat challenge as too little too late. The House is the judge of its members' qualifications, and it can choose to reject the result reported by state election authorities, as it did earlier this year in the controversy over the 8th District of Indiana. But in that case the challenging candidate was ahead until thousands of votes were thrown out by partisan officials -- a situation sufficiently fishy to justify a House recount.

There was much in the counting of ballots in Guam that will remind aficionados of the rough-and- ready balloting on much of the mainland in the 19th century and in some places well into the 1980s. But in this case the result, however surprising, was always the same, and the margin wide enough to make it appear that Mr. Blaz won the required majority. The House should take seriously the right of American citizens in territories such as Guam to be represented as they choose. But in this case that probably means recognizing the reported result rather than investigating it as in the Indiana 8th.