Sorry about the late response.
One other thing you might try is tightening up the primary suspension. If it is not tight enough, it would require the secondary suspension to be pulled tighter to get the quilt to hug the bottom of the hammock. The tighter that secondary suspension is, the thinner it gets and the easier it is to slip though the line locs. Some of the other suggestions made are great solutions as well.
You probably know how to do it, but for those that do not, tightening the main suspension is simply a matter of adding another over hand knot a few inches down from the original over hand knot.