The etiquette is in what you do about it if they've moved it from the way you had it. You do them a favor and tell them about it, that's all. I tell bike shops about it if anything's wrong when I've had something done. One thing I've learned to do is to check the torque on my cassette if I even think they might have messed with it - that's after having a cassette come completely loose on a ride. I've found it too loose a couple times since then, different shops.
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