I just got a new bass by mail and there's something odd about it. Whenever I pluck the open E string, I swear there's a high-pitched harmonic that accompanies it. I've never even heard of something like this and tried a couple searches with no luck. It's definitely heard acoustically (unplugged). It's loud enough that I cannot figure out if it is also coming through the amp, because I'm just playing on low volume with the practice amp. My feeling is that it is not coming through the amp. Is there something in the setup that could cause this? I've put new strings, adjusted the neck, and fixed intonation (can't lower action b/c I can't find my stupid tool!). Any guidance on this would be appreciated. It's so slight that I think I might be losing my mind! ...also my wife says she doesn't hear anything...so...um ya...it's a real possibility.