This scene reminded me of when they were trapped on the island. She was tsundere then too.
However, fellow KallenxLulu shippers, worry not! During her talk with Nunnaly she likened Lelouch to her older brother, the one who was her whole reason for fighting. She was probably wet just thinking about him.
Also, Suzaku doesn't seem to care for Kallen beyond as a friend. Hell, Luciano pointed out that it seems he was more interested in Anya.