While most people consider an occasional form of pain as superficial and that it will simply pass, back pain and other forms of pain is the way your body tells you something isn't right. The pain is your bodies way of signaling that a limit has been reached or a problem has developed. Our bodies generally are able to adapt, but when the pain becomes chronic or last for extended periods of time, if the underlying problem remains unattended, the problem can slowly worsen until it becomes more difficult and expensive to resolve.
As a comparison, think of your body like an automobile. If your oil needs to be changed, it can still operate in what appears to be a normal capacity. If the oil is not changed, the engine parts that it protects can start overheating, deteriorating, become less stable, and over a period of time cause additional problems to your automobile which are much more costly than if you had just changed your cars oil when it needed it.
Our bodies are no different. Pain is like the oil light in your car. Left unchecked or ignored, what you may consider "some back pain" can lead to other health issues.
As we get older, just a little pain becomes a more serious issue. Every cell in your body is like a copy machine. Each new cell is essentially a photo copy of old cell which it replaced. If you tool an original document and photo copied it once, took that copy and copied it one, and kept repeating the process, with each copy made the quality of the document will diminish. That is exactly what happens with the cells in our body.
Therefore, as an individual gets older, in order for our bodies to function in it's optimum capacity, it is important to ensure minor problems in our bodies do not become more serious problems. When we experience pain, addressing the cause and solution is imperative to the normal function of our body.
So is some back pain normal? From a medical aspect and for the harmonious function of our body... the answer is no. It is a clear sign that something is wrong, and needs to be fixed.