Lump-after a masectomy done 6yrs ago

Should I be worried? My mother had breast cancer twice and had a masectomy about 6yrs ago. Just yesterday her doctor found two lumps where her breast was removed. She was referred back to her surgeon and will be having a mammogram next week. Is this normal?

[Cleveland Clinic]

Dear rcalderon,  Further evaluation of a new lump is appropriate.  The determination of the type of evaluation is based on several factors including type of reconstruction after the mastectomy.  Having her surgeon involved in this evaluation process is appropriate.