I have developed several rubbery lumps just under the skin - over time. they do not hurt and seem to stay same size - have not seen doctor, should i?

Lipomas: These are most likely benign fatty growths. Normally, our fat grows in a sheet - a layer that keeps us insulated from cold & trauma, and it's also a source of energy storage. Occasionally, this fatty layer may develop a swirl of fat in it that you can feel. It can be like an m&m or a marble, or even a cluster of marbles. You really don't need to do anything with them unless they are bothering you.