tdracer
From
https://airwaysmag.com/airlines/airl...-737-max-jets/
"American said in a statement that only the planes it received after the return of the MAX to service were affected."
I assume this means planes they took delivery of after the November '20 re-cert. That's not a lot of service for things to come loose. I don't think they do any sorts of periodic checks on the system connections over such short intervals. So I suspect this was discovered when chasing down some sort of malfunction or anomaly.