Because I;m not sure how to interpret "sweet and sour" outside of a food context, I'm adlibbing to say: terse, because Lex is a cautious guy with an agenda he intends to achieve (even if he takes a little break or two). *EG*

Also:

"Um, well," he gives Lex a shy, hesitant glance, "maybe I just need special attention?"

Clark! You sly dog! Hee!