What I loved about the scene where Lois was organising everyone? It took us right back to her days as Jonathan's campaign mangager. And remember it was in that season that Clark and Lana broke up, and Lois gave him that piggy bank. Like other here, I saw desire on Clark's face,, it really did remind me of the first time he and Lana made love ( as noted by someone else the expression is damn near indentical)
I think he's realising that the piggy bank close to being ready to open, and the 'harley' is much closer than he ever realised. So that makes him guarded. He's at least considering the possibility of them together, as we saw by the end scene of them commited so *shrugs*