It was trouble enough last summer when bureaucratic delays and neighborhood opposition held up efforts by House Minority Leader Robert H. Michel (R-Ill.) to build a two-car garage behind his Capitol Hill town house. It took months to get the permits and hassles ironed out.

Yesterday, a District government official sent Michel a letter telling him to get proper permits for the garage or tear the whole thing down within five days.

"A recent inspect of referenced premises discloses new construction (garage)," said the letter signed by James A. Shelton, construction and inspection branch of the Department of Consumer and Regulatory Affairs. The letter said no permit existed for it. "Therefore, you are ordered to stop all work, submit necessary plans, plat and application . . . or remove the referenced construction with five days."

It was all a mistake, one quashed quickly by Julius Hobson Jr., the District government's liaison to Capitol Hill. "I haven't been that angry in a long time," said Hobson, who talked to Michel personally about 5 p.m. yesterday to assure him that the letter had been sent in error and nothing had to be done about the garage. Hobson said he apologized on behalf of the city and informed Mayor Marion Barry.

The two-car brick garage at Michel's home near Eighth Street and Pennsylvania Avenue SE drew attention in January 1986 when the local Advisory Neighborhood Commission refused to endorse it.

Yesterday, Michel's office was surprised that the issue had surfaced again. "He is trying to take it in a very lighthearted manner," said Johanna Schneider, Michel's press secretary. "It's just been a laughingstock."