It's complicated. I was on tow at a contest. The glider on tow ahead of us released and did a shallow 270, crossing back over the path he'd just flown.. I watch him come around as my towplane continued to climb. I should have said something but I judged we'd be clear so didn't (mistake). The glider pilot saw us and, startled, dove under our path (he was under it anyway by then) yelling about almost being hit by the towplane. The towpilot admitted he never saw the glider. Lotta of mistakes, including my own. A learning experience. Both other pilots were older/experienced/high time.