Her whimper is what gets his focus snapped back into the 'reality' they have created inside the confines of this spell and ritual, and for an instant he is concerned he has hurt her in some way - but then it clicks that she is not in pain, but actually wanting more from him...

"Forgive my distraction with my words," he apologizes, leaning closer, pressing his lips to her shoulder as he bows his head. "When I am nervous, I find I chatter..."

She is wanting more from him and he will give it to her, adding a third finger to the stroking he is doing, teasing her clit with his thumb as he resumes his earlier 'rhythm' he had set.