Spike is 8 months old and has gone on mini hunger strikes like you describe since he was about 5 months old. Reptiles can go far longer without eating than most people are comfortable letting them go. As long as your dragon is healthy and getting the right amount of uvb,heat, calcium and vitamins, I wouldn't worry about his not eating. He will eat when he is hungry. Spike sometimes goes 3 or 4 days without eating, but always starts back up when he gets hungry.
Eric