I believe it is every 72,000 miles or 6 years - which is slightly odd as my MG TF with a 1.8 K series is every 60,000 or 4 years and as far as I know the belts and ancillaries are the same!!
60,000miles would be the magic figure I went for also; though at five years old it certainly could hurt to have it done at the next major service - more for the fact that the tensioner could be past its best days than anything. That said; it's not my money!