focal nodule assymetry

Hi,

My mom recently got a mammogram and the findings indicated "there is a focal nodular asymmetry in the posterior central to upper left breast as seen on the MLO view only". So, she has to go back in. There were "no suspicious microcalicfications in either breast"

Naturally I'm really worried. Do you think that because its only showing on one view that that is a good sign or that whatever it is is very tiny??