Good point. If it flaps about it might bend the titanium rod as well. Is there anything to stabilise the plane along the roll-axis while on the launcher?
Perhaps you could have the trailing edge of the wings rest inside a couple of forward-facing (teflon-coated?) U-shaped brackets while in the launch position. No need for them to touch, but it might help to stabilise the plane in case of turbulence.
Not as elegant as Tempest8008's idea, only U-brackets would distribute the restraining force over both wings instead of just one.