Here's a suggestion for you. Tighten the crosstip screws on the face of the holster to increase pressure across the entire pistol and see if that helps. It works for me with my XD-M Elite.
Yeah I started cranking them down to see but the bushings are so thick not sure it will really give much. Also leaving Hellcat out of holster a few days and carrying XDs 4.0 to see if trigger guard recovers or not. More out of curiosity than anything.