I got the impression Ryuuko didn't care much for Satsuki's confession; her response was pretty matter of fact-ish and didn't get particularly mad until she realized she had been used. Still, the end of the episode felt a little weird considering the preview for episode 13 specifically mentions that Ryuuko is doubting herself and hesitates to use Senketsu again.
It could be the intervening time in between her reawakening and that conversation with Satsuki, after all, the mentioned it had been a few days transpiration.