She just has nothing to say. he's got her speechless
[in return, Buffy makes a sort of gasp when he flips her onto her back. It's more out of him hovering over her and being so close, rather than actual surprise at the move. She's literally breathless for a few seconds while her heart races, pounding in her chest. Clearly, sparring is no longer foremost on her mind. This feels a lot more like Sophomore year before her seventeenth birthday and that's not a bad thing.]