The slide-outs flex a lot more than most people are aware of. Floor and walls do not move together, so if the dinette is attached to both and a lot of weight is carried inside the dinette base, what you are seeing is very likely. Not sure what you can do about it. Also, it is not a good idea to walk on the slide-out floor with the s.o. retracted.
Texas Baptist Men-Retiree Builders member since '01
13 Silverado 3500HD D/A, 2wd CCSB srw, custom RKI bed
11 Cruiser CF32MK