It's generally a good idea and part of the whole 'preventative maintenance' thing. You can hold off if you want and it won't be a big deal, as I'm doing right now, and you'll probably only lose a little power and efficiency and won't hurt anything. I'd love to get mine done though, they're ticking like crazy at certain throttle positions.

It can be very difficult to tell if they're actually ticking, and the noise won't appear obvious at idle until they're really bad.