5.3l piston problems?

I just bought a 2000 truck with a 5.3l. It started making an engine noise soon after I got it. Truck has less than 100000km on it. When you disconnect the coil for #4 cyl, the noise goes away. Dealer says I have a bad piston in hole #4, and will pay to replace. I have since been told that these engines are prone to piston problems. Is this true?
Also, will replacing 1 piston solve the problem? Will I have problems with the others down the road?

yes they all have piston slap !