Cause/symptom of repetitive sentence in mild dementia (prior stokes; Broca's apashia)?

My mom has had two strokes (we know of) starting five years ago and with Broca's aphasia as a result, but her speech has come back almost 100%. Recently, we've seen her state things repetitively and it's kind of scaring us. A few weeks ago, it was "No one comes home to take care of me." over and over and over. And it wasn't woven into conversation, it was just stating a sentence. Today for instance, she was staring at her hand for some time and then kept repeating, "How did I get so old?" I was nonchalantly recording this because I needed to show it to family members. She must have said it ten times in rapid succession. I know AD patients have repetitive phrases and questions, but she's never had a diagnosis of AD.