Biopsy Results Different Second Time?

had partial shave biopsy on mole (NP thought possibly mildly atypical). Biopsy said benign with no atypia. 5 months later it regrew much darker and looked irregular. 2nd biopsy (punch excision with margins) said mildly atypical. Does that mean the first biopsy was wrong, it went from normal to atypical within 5 months, or it appeared atypical under the microscope 2nd time bc it was a recurrent nevus? Should i question the accuracy of my other shave biopsies? I am 26 yo female, high risk for melanoma.