Long tap root in aerogarden pro, but no plant?

The oddest thing...

If one were to germinate a seed in the Aerogarden Pro, and the seed were to germinate very quickly, but after 5 full days have passed and the tap root is 2.5 inches long and there is no flowering - I mean the tap root is long and healthy but the seed hasn't popped for the stem yet - what's going on?

Is the seed doomed to failure? The Aerogarden Pro is set to Tomato setting, but the only thing growing is the tap root, and it is growing real good. Will I have to intervene somehow and pop the seed with tweezers, or would that be asking for instant death for the seedling? Expensive female seed and it sank in distilled water right before germinating it, so seed should've been good.

Thank ya -

Let it happen naturally.

I hope it does happen naturally, indeed... but isn't it uncommon that 5 days grows 2.5 inches of root and i open slit in grow media sponge and top of seed where stem comes out is still sealed tightly?