The most common reasons for a grinding noise is a worn out synchronizer, bearings, or gears. But it can also happen if for some reason the transmission is running out of oil or the oil has been contaminated. Other problems that can lead to a grinding noise include bad speedometer drive gears or too much end play at the input (or output) gear end.
I'm not aware of a TSB (technical service bulletin) reported specifically for the transmission on this model. The most common issue on this model has to do with the engine, cooling, and fuel systems. But you might want to call your local dealer to make sure. It'll be cheaper to have it diagnosed at a transmission shop first, then make a decision accordingly.