Cassian makes a bit of a show of leaning away to look left, than right, as if concerned there might be eavesdroppers or peeping toms about. As if either of them needed to crane themselves around for several full seconds to get an impression of the area.

"No one's nearby right now," he informs her helpfully with his own matching grin. Which means he can't be blamed if he goes in for another kiss, right? That's the logic and he's sticking to it.

It's soft and quick because he's decided, right now in this moment, that he wants to kiss her entire face until she laughs, or pushes him away, or hopefully both.

(Also because he didn't before, and Cassian is good at fostering regrets for the things he didn't do.)