I’ve tended to imagine Ash and Misty falling into a relationship almost by accident, neither one directly admitting anything. They’d either semi-consciously start dating after some rather mundane incident makes things clear for them without anything being said, or they’d have an impulsive burst of affection after a life-threatening adventure.
I may have to rethink that theory, because if this episode didn’t demonstrate that Misty’s grown confident enough about her feelings to overtly flirt with Ash, then I have a seriously flawed notion of what flirting is.