In the middle of my PM flying the second leg and had a question about the rotation process. The FO rotated the aircraft beautifully, but tried to continue the pitch attitude instead of leaving it where the flight director recommends (so it was basically as if the computer continued to command pitch beyond the FD command). 

I had to jump in to prevent a stall situation from happening. Is this normal behavior? Or should the FO stop applying back pressure once it meets the recommended cross hairs of the FD? Or did I do something wrong?

Making the computer fly the plane is tricky.

This is why the virtual PF will ask you to turn on the Autopilot at the earliest possible time.

Get the autopilot on asap 🙂

That should happen right around 15 degrees on rotation.

And once the autopilot is on, then there's no problem anymore flying.