Seeing the reaction he had anticipated, Leo broke into a bright smile and tapped the tip of Hera's nose. "Not that, silly..." he said, understanding what Hera was thinking. This only made Hera's face redden even more. His statement, "Not that," implied that he might have said something indecent at the time due to the effects of the drug, or perhaps even done more than just kiss Hera. This realization dawned on both Zhane and Dave, causing a shift in their composed facades.
They understood that Hera would want to keep everything that happened private between herself and the individual involved. However, hearing little bits and pieces to it while Leo was acting so lovey-dovey with Hera made both Dave and Zhane angry and flustered. They felt left in the dark, unaware of the full extent of the events beyond what they had been told, and the uncertainty only fueled their frustration.