Routine service

[Vanessa CW21]

The powder they're talking about, is most likely "metal dust" created by the rotor, scraping the metal bridges because the rotor axle was broken. The axle can break with any impact, and has nothing to do with the watch being serviced a day, a month, or a year ago, it just happens!
The reversing wheels at the other hand might have been affected by the metal dust, but than this watch should have been running like this (with the broken axle) for a long time!
My guess is that the previous watchmaker wasn't as "skilled", and this new watchmaker is dealing with the consequences.
Every BB watchmaker has gone to a watchmaking school, which is usually a 2 year WOSTEP program. After that they are trained at the headquarters for whatever time needed to be very knowledgeable about Rolex repairs. And they go to Rolex to receive their in-house training.
Nobody's perfect, and people can make mistakes... the fact that they're taking the proper steps to correct these mistakes proves their integrity and professionalism.

Just my .02!

Vanessa