Mycroft let none of the distaste or surprise show on his face. He had excellent control of his microexpressions, and even someone as skilled in the art of reading people as Moriarty would have trouble sussing out exactly what Mycroft was feeling. The only person who ever came close on a regular basis was Sherlock, and even his deductions were colored by personal bias and history.
"I'm told even the most dedicated of civil servants requires rest and relaxation from time to time," he replied coolly. "I merely capitalized on an opportunity presented to me." There was no need for Mycroft to elaborate further; if Moriarty wanted to draw his own conclusions he was free to do so. Likewise, Mycroft had many an idea why Moriarty himself was in Preya; only time would tell which was true.