You need to be worried. Sounds like a circulatory problem one way or another. Whether it is the early signs of PAD (often called hardening of the arteries) which is affecting the arteries, or an early indication of heart problems, this type of symtom is generally associated with clogged arteries somewhere in the body. If your mom is overweight
(or had been for a long time), has little exercise, has dental problems, and/or smokes it is likely she has she has some form of arterial disease. Essentially what is happening is there is not enough oxygen
being delivered to parts of the body because the blood supply is blocked or slowed down. Plaque
(the same stuff on your teeth) forms in the blood vessels and blocks the vessels much like muck in your plumbing pipes block the flow of water. Treatment, depending upon the seriousness of the disease, can range from surgery where the vessels are widened thru shunts or balloons, to by-pass surgery of the heart, to simple lifestyle changes such as a better diet, exercising, quitting (or at least cutting down dramatically) smoking
, etc. I think you already have a sense that something is wrong, and what it is, because you put your quesiton in the correct category. Your mom needs to see a doctor. If it is nothing serious, then great! If it is something serious, you've caught it in the bud.