I was actually thinking that he has already figured it out but is pulling a Jim Gordon and is refusing to acknowledge it because he's decided that he doesn't want to know.
It's got to be pretty obvious. Yea in season one Ollie was suspected of being the vigilante, but they appeared n two different places. Now Lance knows the Arrow has a team, he has to know the truth.
In one of those season ending death bed moments, Ollie will tell him and Lance will just say 'yea kid, I know."