I always do the piston and rings together. Its not that much more $$ or time wise, considering you have to pull all the gaskets, drop coolant, blah blah blah. In the end cheap insurance.
In my 2010 300 the piston was slappin around at 75hrs although the ring gap only measured in around 0.5mm
I'd also suggest throwing a fresh little end bearing in too. Again, just for cheap insurance.