This isn't that surprising. Lee Hsien Loong studied at Trinity College, Cambridge, where he was Senior Wrangler, and graduated with a first class honours in mathematics and a Diploma in Computer Science (with distinction).
He's mentioned in the past that he briefly considered a career in academia (Mathematics). That didn't happen, of course. (source: http://www.moe.gov.sg/media/speeches/2003/sp20030603.htm)