It seems like the ones that are "fine" would still have the same propensity to someday not be "fine".
This Safety Alert applies to all M&P Shield pistols manufactured before August 19, 2013. We believe this condition is largely limited to recently manufactured M&P Shield pistols. However, out of an abundance of caution, we are asking all consumers of all M&P Shields manufactured before August 19, 2013 to immediately inspect their pistols for this condition.
Originally posted by spacecoast
While the symptom seems to be clear (plastic tab not reappearing), I don't see any description of the cause. If it was a manufacturing defect on some of the tabs, that should be noted.