My right grip screws started backing out during range excursions, so I took the opportunity to remove the grip and have a look around. On reassembly, I had a little trouble getting the trigger spring to fully seat, same as described above.
For me, what worked well to resolve this was to hold the right side of the spring in place with my left index finger, while lightly pressing the end of a hex-key against the open end of the spring (a little above where the red arrow is pointing in the posted image). That created enough room for the spring to slip easily over the pin and seat properly.
I was hesitant to try permanently altering the bend in the spring, because I didn't want to risk metal fatigue or simply opening it too far. Additionally, once assembled, the spring tension around the pin helps hold the spring in place. Seems like a good thing.
p.s. A light touch of Loc-tite blue and fresh grip screws eliminated the back-out problem.