It's more than likely form. I agree with that. BUT, one statement you made makes me want to have you check a couple other things. You said, "depending on which arrow". It could be the arrows. Also, if you bought a bow one month ago and have made NO adjustments since you got it.... string stretch could be playing on it too. Number or sort your arrows somehow and see if it's the same arrow. It may be a matter of turning the nocks a tad or something if you're getting contact. Lots of things could cause it. A high left tear can also indicate a spine problem. You have to dig a little. First make sure of your arrow selection. I guess the quickest way to check spine would be to put on a lighter head. Charts are a guide, not an absolute. If you're border line and plan on shooting broadheads you should always error on the side of stiff.