Just re-entering the hobby after about a 14 year layoff it appears that most of the ARF's don't have or recommend the center wing joint being fiberglassed.

I attended another clubs fun-fly this last weekend where one of our club's instructors trainer had a similiar wing failure as well. Many structural failures occur from fatigue even on trainers from continual over G-ing with poor structural support. Adding fiberglass to the mid section of the wing section would most likely prevent many failures.