The problem is not the trigger mechanism itself. The problem is adhesive put on the guns which might have seeped into parts of the trigger where it does not belong. Causes the trigger to potentially gum up and not engage the sear correctly allowing the rifle to fire without the trigger being pulled. They inspect to see if there is gunk in the trigger, clean it with solvent, oil lightly, test, and send it back to you. Once it is cleaned the trigger is fine.
FYI:
Old Remington 700 triggers are dangerous because they are adjustable. The trigger has adjustment screws which are set by the factory then covered with shellac to keep them from turning. Unfortunately the old trigger design did not include stops so the sear adjustment can be backed out enough to have very little or no engagement, resulting in guns that fired when bumped or even the moment you closed the bolt or dissengaged the safety. The updated trigger added a stop to the adjustments.
Years ago magazines printed how-to articles about "improving" the triggers, which encouraged a lot of home gunsmithing attempts. Even if it was safe when complete, regular dosing with penetrating oils on a trigger that did not have the shellac replaced could result in the sear adjustments slowly backing out under recoil. Remington has been sued plenty over this issue. Company argued they don't advertise the adjustability and glue the settings in place with tests showing the trigger should remain safe during lifetime of use. Courts said doesn't matter because the company knew people were jacking with the trigger and failed to do something to prevent it.
