Thank you so much for your input last week on how to go about fixing a small tear in a quilt top.
I decided to purchase some Pellon 931TD midweight fusible (one-sided fusible) to slip in under the tear and iron in place. The tear is no longer gaping, and with continued gentle handling, I think it will be OK. For the record, it took me 5 minutes to even find the tear again to make the repair, so I am going to work on getting the quilt submitted to a few shows!
Below are 2 before and after shots side by side. The tear is honestly quite small and hard to find on the quilt; these photographs really exaggerate its size.