"Hm," Rodney says, lips glancing off John's cheek, Rodney's mind already in the labs and settling down at his workstation to do battle once more with the automatic quarantine protocols, John just some guy Rodney happens to have smooched on his way out the door.
John catches his wrist and kisses him hard on the mouth, just to stop him, for a second, to see the sweetly befuddled look on his face:
Oh, you. What are you still doing here?
Then it's gone, along with Rodney, because when genius strikes it takes more than a kiss to slow him down.