So...I did a neck swap on an old Jazz clone this past week and am having a weird buzz in one spot. Not the normal "low/hi fret" buzz, or loose string in the nut, but actually behind the fretted note. Weirder yet, only on the "C" note, 8th fret of the E-string. Basically, hit this specific "C" and get a weird resonant rattle between the nut and the fret. Never had this happen before. What gives?