Dear latronica: Moving during the mammogram may distort the image if the movement occured at the precise time the film was taken or if the movement were severe enough to move the tissue out of the film. Usually, the film is checked to be sure it is a "good" film but each place is different and hard to know if this is the case. If they have called to retake it, it could mean that there is something on the film they want to further evaluate or it could mean the quality of the first film is not good. You should ask when you go.
thank you for replying and that was just the case! Just got back and all is well for another year!
thank you again for a wonderful site!