It should be okay but it will be awkward moving the tank about in the future (the tank's frame could hang on the cabinet pulling it forward for cleaning in other words). There is going to be some stress on the glass where it rests on the back edge of the cabinet but it should be okay as long as you don't use it as an aquarium.

Putting a slat between the glass and cabinet to level it up would be a good way to slide it around as the case arises.