I would check for anything loose anywhere on the bass. Try "thumping" the bass with your fist and listen for anything buzzing or rattling. I would also tighten the truss rod about 1/8th turn. Just enough to make sure it's not rattling/buzzing.
2012 RIC 4003 M-G, 2004 Fender Jaguar, 2011 Fender American Special P-Bass, Hartke LH1000, Carvin BX500, Avatar B210 & B115, Rickenbacker Club # 496, Jaguar club #103