Additional information from site:

Issue Overview

In rare instances, if the left and right frame inserts of Ruger SR22 pistols are not properly secured together, the firing pin blocker lifter and hammer block can move independently of each other, potentially rendering them ineffective. If this situation occurs, the pistol will intermittently exhibit a “slack” single-action trigger and has the potential to discharge if decocked over a live round. (Watch our overview video)

NOTE: A “slack” single-action trigger occurs if, while operating the pistol in single-action mode with a magazine inserted, the slide forward, and the manual safety disengaged, a trigger pull does not encounter resistance and the hammer does not fall.