Re: Is this TMJ?
If it happens all the time and is chronic then it is an issue of tmj joint dysfunction. Some people remain asymptomatic meaning that they lead normal pain free lives and only have infrequent related symptoms result such as an occassional migraine or jaw pain etc - so for those treatment is not always necessary. It should be treated however if the popping develops more into a grating noise which may indicate the joint has deteriorated to the point there is now bone on bone contact. He may want to at least see a tmj dentist as this type of condtion responds well during the early stages of dysfunction to proactive and preventative treatment such as wearing a night guard and may slow any further progression of joint wear and tear.