Watch him. If all is well, I wouldn't worry for the time being. Certainly, milk is the most important source of nutrition till 12 months, so at this age most babies wouldn't be eating much anyway. It's about the experience.
Precisely when babies *need* food is variable. Some time between 6-12 months the iron stores *start* to run out, which is why we have the 6 month recommendation. That doesn't mean all babies need other sources of nutrition from 6 months. In fact, many are just fine not eating till much later.
Am I right in remembering food allergies or sensitivities?