I think Suzuki used a redesigned plug starting with either the 2002 or 2003 models so that it shouldn't simply begin to leak on its own.  However, the manual still doesn't call for any sealant to be used so if a dealership p[erforms the 600 mile maintenance and actually retorques the head bolts, it's possible it may leak if they follow the service manual and don't use any sealant when they replace the plug.