Can 3rd gear synchronizer cause other parts too break?

[5MTcamry]

Hey everyone,

I have a 2007 camry, 2.4 L 5 manual transmission. I noticed that when I downshift to third gear (from 4th or 5th) I feel and hear a small grinding noise. I took it to Toyota and the mechanic told me: "It's not going to break other parts or transmission, so it does not need to be fixed unless the sound/feel is bothering you"

The sound and feel of grind when I downshift (up-shift is ok) to 3rd is fine with me, but I want to be 100% sure that it will not cause other problems in the long run. I intend to keep this car for a while so wanted to make sure.

Can you please advise? Should I have the tyranny rebuilt or should I leave it?

Thanks