I don't have a side dinette, but I know Scamp
recommends lowering the main dinette for travel. It might be a good idea for the side dinette, too. The weight
of the table top combined with road vibrations is probably what got it wedged in there so tightly.
I had a van once with a pedestal table, and the advice given is exactly what I had to do sometimes. Never had to resort to WD-40, though.