Suspicious calcifications a year after mastectomy

Not sure about the dcis, that sometimes is missed if no calcifications are present I believe. I had a 2.5cm tumour with nearly 6cm of calcifications and had to have a mastectomy on my left side last July. I went back for my annual mammogram two weeks ago and was recalled for a suspicious cluster of calcifications. I had another biopsy today. The odd thing is that I was told today that the cluster wasn't presenting itself on the mammogram and the calcifications were scattered but they biopsied the exact spot I was told the cluster was. They also said the calcifications were on my mammogram last year and hadn't changed much in appearance. I asked why on earth they hadn't been checked out last year and got some nonsense reply. I'm not quite sure what to believe.