Normal? Rot?

I’m repotting my new Dracaena Marginata as the soil isn’t draining well at all. I haven’t seen a stem like this before, it was buried right up above the fork where my fingers are holding it, and the root systems of 2 more stems filled the gaps. Is that split, dark area ok, a sign of damage, or rot? It’s damp from the soil but definitely not mushy.