Hey guys, I love my SUB (I have two) and have noticed on my Mint Green one I'm getting a buzz/vibration down in the bridge when I play my A string. It isn't fret buzz because I've done a full set up on it. Likewise, I play the a string and let the buzz sound happen and try to stop it. I've put an allen wrench in all the saddle screws, pushed down on everything, muted the springs on the posts, and nothing will stop the vibration. Could it be the string doing this?