She's aware of the things she should say in the moment...well, some of them anyway. But she figures they should solve their current dilemma first.

"What's your suspicion?" The Doctor turns her attention to examining the mask on River's face. She reaches out a hand to lightly trace a finger along the line of demarcation between skin and mask. It looks like it should hurt and yet for The Doctor, it's only an irritation. She assumes the same is true for River.