The only reason he really noticed her tongue was because he'd been smirking at her anyway - he wondered if there would come a time when he would stop being so oblivious to things - and on the heels of that thought, he wondered if she was being intentional with the way her tongue was moving on the glass. He reasoned she... probably was. And that turned him on more than he really thought it should have, and he stared at her unabashedly, his mouth falling open slightly.
Neville was far less oblivious to the situation, and smiled slightly. It was nice. They seemed to get along well, and had a good rapport. He could release on this - it had just been vague inklings of interest anyway.
Tilting his head in Ace's direction, he teased lightly. "These are really the sort of 'If I tell you, I'll have to kill you' secrets?" he said, amused. "In this day and age?"