If the 'airline suspected something was up', the aircraft would not have been allowed to fly for 2 further days.
Well I guess that would depend on the results of a phase I inspection, assuming one was conducted at the time. Still, it sounds as though the crew didn't consider the landing to be 'hard', so didn't report it as such and therefore no inspection was triggered at the time. That didn't occur until later, when the QAR data was analysed as part of the airline's FOQA program.