It is most likely/definitely fan service from the anime producers. You know this scene will be the inspiration of countless pixiv drawings and stories. From the ‘troll face’, to vol. 6 preview omake, and now, the kiss of luck. Let’s take a look at what some creative minds have brought..
(I’m only showing a clip of the drawings, follow the links to view the whole thing)
ジャンがキスしたと聞いて【17話】 by まろ犬 on pixiv
Judge: Mr. Kirstein. (As) This is an important matter regarding humanity’s survival. Please repeat, was your first kiss really given to a human girl?
Jean: It’s….(to) Three Dimensional Maneuver Gear…
(Those are only rough translation, but the general idea’s there.)
UPDATE EDIT: Mr. K. is in chapter 48.