If you are certain that your crankcase has never been filled the synthetic oil, then you'll be fine. You would probably still want to change them out, especially since your over the 100 hour maintenance mark.
The ceramic washers became a problem when shops assumed that becaused the N/A motors used synthectic oils, the SC and SCIC motors would to. The synthetic oil caused the ceramic washers to be to slippery to efficiently control the slippage of the charger gear, then it caused the rapid break-down, until they disentagrated, stopping up your internal oil porting with fine particles of the ceramic washers.
If you've not used the synth oil, pull the charger for the 100 hour rebuild, use the new washers. You should not have to pull the motor to do a clean out of the system, as long as you can account for the entire washer set.