That's because it's in your nature to worry about others rather than yourself, even when you should be concerned.

[There's a sharpness in his voice, and he doesn't know where it comes from, still mostly caught up in the false memories of this dream.

Nonetheless, Zack's fate matters to him. He fills the kettle, puts it on the stove.]

I worry about you. You should talk to the professor, when he wakes up. He might be able to help you. [He has a great respect for Gast's work. Whatever's wrong with Zack, if anyone could help, the professor can.]