Monday, May 20, 2013
The highlighted (Straits Times Interactive, 17 May 2013) should not be hyphenated.
It is hyphenated only if it is used atributively; that is, it comes before a noun, e.g. a 38-year-old footballer. Note also the singular unit of measure in this case, i.e. year (not years).
Otherwise, there are no hyphens, and the unit of measure is plural; e.g. The footballer is 38 years old.