There are some pretty major gaps between the floor of our modular casa2g90 oven and the dome walls. We've made them pretty even on all sides and the gaps probably range from 1/2 an inch to 1/4 inch all the way around. In the pictures I've seen of these ovens, there are no gaps at all. Is this a problem? do we have a defective oven? Are we supposed to fill this with mortar?