As Luffy arrived, Sai rose from his seat. The pirate captain was smiling, so the ninja kept up his own in return. Usopp seemed to have been right in that Luffy wasn't upset with him, but he could never be sure. Starting the night off on the wrong foot would only make their tasks more difficult to achieve.

"Good evening," he greeted. "I hope you weren't injured too badly last night, and I apologize for my actions." He may not be angry, but common courtesy still deemed an apology necessary. It would also reassure the pirate that he wasn't on the side of the institute anymore, in the event that he'd had any doubts.