That sounds about right. Stoneyfield farm is an organic brand and as far as I know, they do not add sugar to their yogurt. Some other brands do add sugar. The difference is in the taste. Try some other yogurt, especially yogurt that is marketed towards kids, and it tastes like candy compared to the natural stuff. Also, some light yogurts have artificial sweeteners added.
So, greek yogurt probably does have less sugar than most other normal yogurt brands, but Stoneyfield farm makes some good stuff. IMO, stick with the natural, regular yogurt. Greek yogurt is much closer to sour cream. I don't know about you, but I'm not a fan of strawberry flavored sour cream.