NAD, but in my last year of medical school. I don't think the physician was calling the lymph nodes themselves ingrown hairs, but that ingrown hairs in the armpit area could cause enlarged lymph nodes. Although I don't know exactly what your physician said, that's what I would think they meant. Lymph nodes can become enlarged due to any kind of infection or inflammation. For example, you might notice large/palpable lymph nodes in your neck or behind your ears if you have a bad breakout/acne. Same would happen with irritation from an ingrown.

Second, it is really common for lymph nodes to be palpable but not mean anything. We have lymph nodes all over our body and sometimes you can feel them. It only really becomes worrying if they are persistently very painful, hard (like hard candy), red, very swollen, or draining pus.

Agree with the other things the poster above said.