Why did you have them tighten the axle bolts?
I was kinda hoping you wouldn't say this. There is a protocol, which calls for replacing both nuts. I'd go back and have them fix this correctly. FWIW I don't think the axle nuts are part of the drive train warranty. Unfortunately.I had the clicking noise when accelerating or decelerating. They put the washers on and I assume used the same nut. I probably should have researchedmore and did it myself since I do a fair amount of work on cars but that is some high torque. They charged a full hour of labor at $160 to do the job. Others here have been charged about $106.
The axle nuts really should be covered by the powertrain warranty of which I only have a few days left. They don't seem to be a wear item and it is just part of the powertrain basically falling apart. Anyone have any good arguments for convincing them it should be covered by the powertrain warranty?