The show which began its limited run March 18 and is set to open April 7 also canceled the March 24 matinee. Lithgow is expected to return to the show March 26.
Joining Weaver and Lithgow in the cast are Danny Burstein, as Gordon, Mrs. Farnsworth's writing instructor, Kate Benson, Fernando Gambaroni and Tarajia Morrell.
In the comedy, Mrs. Farnsworth is writing a book about an old lover, a profligate WASP from a wealthy clan who sounds suspiciously like George W. Bush.
The piece is directed by Jim Simpson, Weaver's husband and the man who runs the Flea. Weaver and Simpson have teamed frequently of late, in such plays as The Guys.
For tickets to Mrs. Farnsworth at the Flea Theater, 41 White Street (located three blocks south of Canal St.), call (212) 352-3101. For more information, visit the website at www.theflea.org.