Ted, I sometimes get that on the other side, but not from riding the bike. If I am diligent about doing exercises 2 or 3 times a week at the gym, it doesn't get me. I'm 57 (today) and would guess your issue is a muscle thing and not a spinal issue.

Try to strenthen that area. I have only been riding semi seriously for a couple of months, but haven't had any back issues, and I do have some back problems doing other things.

John