I wouldn't worry about the delay... sometimes those pathology reports take slightly longer than anticipated. From my own personal experience, and the experiences that others have shared with me, one usually receives immediate or quick notification if something questionable or suspicious is found... best wishes and good luck to your mom.
I am sure that the delay is not necessarily because of bad news...the waiting is always so stressful for so many of us, but that's the way it goes.Try to be patient since all the work that has to be done takes time...some get the results within 3 days while others take much longer,but whether soon or later it has nothing to do with good or bad news.You can certainly call her physician to find out, I don't see anything wrong in that.Best wishes for a good prognosis.Take care and good luck.