Have the exact same thing on my trainer. it's a flat bottom with quiet a lot dehidral.

Take it inverted, and I have to give it full elevator to keep it level. It's due to the flat bottom as already mentioned. Keeping it level is a great challenge, since the dehidral is then anhidral, and the wings constantly want to drop the either side. thus required constant aileron feedback. However, if you can fly inverted with a trainer, you'll have a blast on a more aerobatic plane when flying inverted !

I've flown my friends plane once (a high wing aero trainer with semi-symm airfoil and no dehidral) and inverted flight was easy!