Slow/Dead Seed Question

I placed two germinated Nirvana seeds into Jiffy Pots (pellets) four days ago. One of the seeds has already penetrated the surface and is about 1 inch out of the dirt (it emerged two days ago), while the other is nowhere to be seen. I very very delicately opened up the soil and saw that the "slow seed" has barely grown past germinating (the tap root is still less than 1/8 inch).

The seeds are the same species/type and I'm worried that one of my seeds is dead. If I can diagnose this early there is still time to germinate a seed and replace the dead seed while still being relatively close in age to her partner.

Is it common that some seeds will start growing faster than others despite being the same strain? In the past all my seeds have penetrated the surface around the same time...

I've had seeds take a day or so longer than their "litter mates" but never more than 2 days later.

Ok, I'll give it another day before I replace it... any more opinions would be awesome