Its my understanding that they cannot identify a remap unless they actually put it on a rolling road and see obvious power gains, so maybe thats why they kept asking the question rather than establishing it for themselves.
....My understanding is that they would have to send the ECU to Germany (probably Bosch) to be certain and that, once there, they would definitely be able to confirm a remap.
If your remap is switchable, like a Revo, you would be wise to switch to Stock for any dealer sessions anyway. My dealer knows about my remap but I still switch to Stock so their work is more reliable.