It ought to make him question what it is that Sylar's promised, but his mind is somewhere else, focused on this mythical lab that Peter Petrelli's supposedly dead father has promised to the lover of his long lost or given away son. "We ought to go then. But first--"

Sylar alluded to Matt that he loved him. And while Mohinder wasn't sure if he felt the same way before Sylar appeared in that doorway a few minutes ago, now? Now he's positive it's true.

He loves him. And his mouth, his lips, feel the need to express that in a deep, intense, and passionate kiss.