I have a bar like that as a spare bar.
Tried to figure out how it could happen.
If something pulls the trigger (red piece) and the metal lever is pointing upwards it can fall back into place before the the trigger is back in place. Maybe the lever can just bounce back too. When i pushed the trigger under load it could get stuck half way up and 3/4 ways up. Then it doesn't need much more to release it. As soon as the preassure got down the trigger immediately went down again.
If you kite with constant high pressure on the chickenloop and it releases, to me it seems like something is chafing on the trigger.
In any case you should learn to reset the quickrelase in deep water if you have any plans to kite more than comfortable swimming distance with gear to nearest safe place.