"Gentle Giant" Ootsuka-kun used Head-Pat, in addition to demonstrating MAD 'sexy time' skills ... IT'S SUPER-EFFECTIVE! Naturally, Erika-chan has to maintain certain appearances in front of her pals; it's a Tsundere thing, which the rest of us might not understand.
Overall Conclusion: "Well Isn't That Cute? ... BUT IT'S RIGHT!"
His seat neighbor has been coming on to him pretty hard for a week. I assumed he did some studying on how to please her for when she finally escalates.