I think it's a combination of both. If you are in pain, you should not run until you find out what is causing your pain. Many times the point of the pain is not the source of the pain. That being said, if what you are experiencing is a little discomfort, I think this is normal, and the olde we are the more recovery time our bodies need, something many master runner's tend to ignore.
Have you ever followed a beginner's running program that helps you build endurance? That may be something to think about.
RUN SPARK STRONG!