On one hand, it's not like he hadn't thought about it before, especially that one time in the Hotel De La Cruz's kitchen... damn.
On the other hand, Lassy was completely inebriated and highly unlikely to remember any of this come the next business day.
"Uh... not to ruin the moment or something but... you're kinda wasted at the moment and shockingly as it might be, I kinda have morals about this kind of thing. Making out when only half the party is sober... know... know what I mean?"