I would say that the off-panel kiss was the big surprise here. Given how methodical the storytelling has been, most of the big moments have been satisfying but not particularly surprising in their presentation.
I’m thinking primarily of the performance of the play and of Sayaka’s confession/Touko’s response—we knew these scenes were coming well ahead of time, and they played out very solidly, but much as we would have expected. (Yuu’s confession is something of an exception to this, especially the point-of-view panels where Yuu covers her eyes and the replay from Touko’s POV.)
The same is true of this sequence, except that where the original kiss in that room was depicted for the audience as well as inadvertently seen by Maki, here it takes place (for now) off-panel—a kind of reverse-callback to that early scene. (I would be very surprised, however, if we don’t get a replay of it from one or the other’s point of view, if in fact the next chapter doesn’t pick up exactly where this one leaves off.)
We’ve been given a number of Big Damn Kisses in this series all along; it’s kind of a sly move to make the one we’ve been waiting for happen (just) off-panel.