A conrod doesn't need to be replaced only when play can be noticed on the small- or big-end side.

A small engine manufacturer in Holland once made a custom conrod for an engine of a friend of mine, the conrod was made as hard as possible, but then broke within 1/4 of a gallon.....

Due to the bend and stretch exersizes a conrod will get in an engine, it needs to have a certain amount of flex. So, even if there is no play on the bushing, it might have small damages inside the conrod itself......