Riku had warned them about being nice to Sora, so that's why they were trying to make a little conversation.
"Sora," Aba said, "What classes are you taking next quarter? Riku was complaining on phone last week that he doesn't have class with you in winter." Their focuses just didn't match up, and Sora's GURs that he wanted verses what Riku wanted didn't mesh with the classes they had to take.