Alright, brought the X to my local dealer yesterday. Technician took out for a test drive and could not replicate the noise...they say there's nothing wrong. It's kind of aggravating that I hear it going over my campus' speed bumps every day but when I need to replicate the noise so the tech can fix it, the car sounds perfect. Might take it to another dealer or an independent BMW tech and have them inspect it too just to be sure.