its either your i shaft( the most common problem they have) or some suspension parts are worn which is highly unlikely unless you drive it like crazy. or if you had your tires rotated they might not have torqued them to specs. but right know with out any other info my guess would be the i shaft there is a bullitin to repostion it and then if it is still popping you have to replace it. but if the tech checks the part number if it is in certain range they just replace it. if it is the new desing then the repossion it. so hope i was some help email me if you have any other questions
Do take it back to the dealer. This car is still under warrenty and they will have to fix it for you. You may need to take the tech and drive him around to duplicate the symptom which should help him identify the problem.