That pain is actually is the Gluteus Medius and piriformis. Now the question, do you sit with the laptop in your lap? Do you sit for long period of time? I am seeing this with many of my clients and runners/triathlons of all ages. First, the heat of laptop tightens your hip muscles. Second, your posture is bad when you drop your head down to read book or laptop or tablet. This strains your neck, shoulders then goes down the back to your hips. Third, when you running do you lean from your back and not engaging your core. This true in long runs. Today, we are seeing more and more bad posture. Many sit for hours in one position which restricts blood flow and tightens the muscles. You need to take breaks every 20 minutes. Fourth for runners and triathletes, most of your training is in one plane, frontal. You need to move in all directions (back, sides) and engage your core, not just forward.
Chad, physical therapist at ProForm has seen many patients come in with these issues. From his input I will discuss what you can do help alleviate some of pain in next post but it is always good to see a physical therapist.