After many years of playing my Shanti SF with medium strings, I tried a set of lights (.012"). I like the feel but I'm getting a buzz from the low E string and a littlemid-board buzzing further up the neck on the wound strings. I'm thinking I need a little more relief. It was pretty flat before with no buzzes, but now it's just a couple of thou. Shoud I be looking to tighten the tension rod a smidge or shimming the saddle slightly?