C77 I Might Give You Arsenic

When he came into the room, his cell phone rang, and he finally pulled his hand away from Doe and went to the kitchen to get some water. She woke up thirsty, actually, and after two large glasses of water, she put the cup down and the man's voice behind her said, "Are you thirsty?"

Why didn't she tell him she was thirsty?

She said perfunctorily, "It's alright