If he hadn't been prepared, Cliffjumper might have pushed Mirage away out of pure reaction and surprise, regardless of the situation and his actual feelings. Since he was prepared, all he did was freeze.

Static brushed against his lips, and Cliffjumper cut off the little squeak that wanted to escape by resetting his vocaliser. Tightened the grip on Mirage's hand, and knew he was blushing.

Which, hopefully, wouldn't reveal that something was off to anyone, but why would a blush do that?

Cliffjumper clung to that thought and managed to not tilt into the brief kiss, or move at all when Mirage straightened back up again and the ambassador stepped forward, arms flung out.

"To a prosperous negotiation!"

The crowd, silent until now, cheered.