Transmission

I have a 92 ranger 3.0 with a 5 speed tranny and sometimes when the tranny is warm and im shifting it into 4th gear it makes a scratching sound. It doesnt sound like its grinding and i dont have trouble shifting it into that gear, but it still makes a noise......anyone know what this could be? I was told it could possibaly be a schronizer going bad but im not sure.