parquetry flooring faults

Hi, Does anyone have any comment on how long it takes for faults/damage due to change in humidity in flooring to show?... clearly it does depend on the weather, but due to the circumstances outlined in the next paragraph I am looking for something more. :) We purchased a property and laid a floor in 2010. Sold it in 2012. The new owner has complaints (which under Finnish law, we now have to respond to:mad:) that the floor was incorrectly laid.....We have a different opinion as we owned the flat for two years and saw no sign of buckling, cracking or any other problem, which could be explained by it being laid incorrectly. Thank you in advance.