It’s possible that he upgraded the transmitter to Traxxas TQi only. TQi offers end point adjustments and possible better control with bluetooth programmability.
From what I have seen and heard from others, it shouldn't matter. That being said, if you feel more comfortable, you can always put a very light coating.
Thanks for pointing it out. Normally on a 1/10 scale, a light coating of grease is required, but on TRX4M it is not mandatory. That being said if you do put grease, make sure that it's a very light coating.