The questions becomes, "Why?" Why is Oliver so animated, and what has changed to allow him be so?
It has everything to do with sending the letter. With that simple action came a certain level of freedom for both Shane, and to a greater extent, Oliver, as they wait for an answer to return. It opens a world of new possibilities and options, and its here we see a glimpse of what it might be like to watch Oliver openly, but cautiously, deal with his feelings, especially towards Shane and those apparently extremely valuable steps.
It's Shane's aloofness as Oliver pulls her into his arms and begins to guide her across the floor that allows Oliver's distress to be on full display. He dominates the conversation---the complete opposite of A Hope & A Future---while simultaneously revealing a sort of boundary he has placed on the use of the steps learned during their brief lessons.
Increasingly frustrated by the fact he can't seem to get her to understand exactly what she did wrong, Oliver brings the "dip" to bear, which, as we well know, is so explicitly and deeply connected to Shane and Oliver's relationship alone. As he pulls Shane back in from the maneuver, the look on her face indicates that the knowledge Oliver has attempted to convey has finally been bestowed upon her.