I agree with Stonecutter, not major yet. But water will eventually work its way down the crack and when it freezes, will expend. If the water gets to the oven, it will be a major problem.
To me it needs to be repaired. Either contact FB or it is mostly something you can do yourself.
How handy are you? If you want send me a PM and I will tell you what materials to use for potential repairs so it won't crack anymore.