Last night I got the following reply from Dan Riccio, Senior Vice President of Hardware Engineering to a note I sent.
Regarding the website article - https://www.macrumors.com/2018/12/19/apple-2018-ipad-pros-ship-bent/ let me clarify, This did not include a company statement and we will be reaching out to outlets to comment on this officially later today.
Relative to the issue you referenced regarding the new iPad Pro, its unibody design meets or exceeds all of Apple's high quality standards of design and precision manufacturing. We’ve carefully engineered it and every part of the manufacturing process is precisely measured and controlled.
Our current specification for iPad Pro flatness is up to 400 microns which is even tighter than previous generations. This 400 micron variance is less than half a millimeter (or the width of fewer than four sheets of paper at most) and this level of flatness won’t change during normal use over the lifetime of the product . Note, these slight variations do not affect the function of the device in any way.