My observations of the KLM checkin in Amsterdam is that they are not the strictest. But that's quite irrelevant for you because Delta handles the KLM flights in the USA. I haven't seen someone singled out there, it seems that all Americans make sure their checked bags are of approved weight.
(Standard "procedure" for bags that are 2 kg overweight in Amsterdam is have the passengers remove the excess, generally it's added to the carry-on.)