Federal Trade Commissioner Patricia Bailey thought there was some mistake when she received an invitation a few days ago to a White House briefing for top women appointees in the Reagan administration.

It turned out that there was a mistake.

Bailey, a Republican whom Jimmy Carter appointed to the FTC in 1979 for an eight-year term, was disinvited a few days later, when a White House aide called to say she should not have received an invitation.

Yesterday, however, the White House said Bailey had not been "disinvited," but that space had been limited to 225 Reagan appointees. "I didn't disinvite her, I'll have to see what happened," said Wendy Borcherdt, special assistant to the president for public liaison. "It's probably because she is a Carter appointee. I'm sure it's a computer error."

The briefing, scheduled for this afternoon, was planned to brief leading women in the Reagan administration on the New Federalism, the budget and the economy, among other matters of current interest. They were advised that after remarks by President Reagan and Vice President Bush, there would be "full" White House press coverage "so wear your finest."

"I very much appreciated being invited and I'm sorry I won't be able to go," Bailey said yesterday.

Bailey, who had made a speech critical of a Reagan budget plan to eliminate the antitrust authority of the FTC, had another brush with fame a year ago. Her name came up at a Reagan press conference when reporter Sarah McClendon of McClendon News Service asked the president why he hadn't appointed Bailey FTC chairman even though she had the backing of Senate Majority Leader Howard Baker and others on the Hill.

"Did you mean to give a signal to other Republicans that if they don't conform, that off will go their heads?" McClendon asked.

Replied the president: "How can you say that about a sweet fellow like me? No, Sarah, no. Miss Bailey was one of the names under consideration . . ."

Borcherdt said today's briefing by top White House officials was both a thank-you and an update to help the appointees when they speak around the country over the next several months.

The White House said that as of Jan. 31, there were 283 women named to senior executive level positions (GS 15-18) who are in substantive policy or administrative roles. The White House has been sensitive to criticism from such groups as the National Women's Political Caucus about the lack of women in top policy positions in this administration.