I'm not saying you have stability issues, I'm saying MY experience with my three folders was EVEN BETTER stability. The reason is physics. Traditional bikes have most of the weight over the back wheel - and that's with the rider somewhat hunched over. Most folding bikes have an upright riding position, which puts even more weight on the back wheel - probably 65% - so only 35% on the front wheel.
IIRC, the first time I read about this was by Dr. Yan Lyansky, owner (still?) of Downtube folding bikes.
That's also why I use about 10 psi lower pressure on my front tires.