>>281942789
She didn't just whisper, on the first page here when she's whispering to him it's obvious with how she gets her mouth close to his ear and hides it with her hand. There's even the onomatopoeia that makes it clear
But then on the last panel we can see she's standing at a good distance from him, so when she replies "You're welcome..." on the next page it's more likely she said it aloud rather than whispering