"Don't you think it's time you were?"

Even if the effects so far are manageable, it seems foolish to test them unnecessarily. They've only been here a few months, so he's not at immediate risk of dying -- but that doesn't mean being at all weakened in the middle of a war was a good plan.

"I asked you to tell me if you started feeling ill."

So she could give him exactly this lecture, yes. But also so she could help him find someone to tether with.