Hm...interesting. I am curious to see how the dealer can tell if the ECU has been reflashed. In order to do that, they would have to pull the ROM off the ECU, do a checksum on it and compare it to the stock image. Either that or they have software to view your maps off the ROM but I am yet to see that at the dealership and they'd still have to pull it off the ECU to check. On top of that, each MY has multiple revisions of the ROM so there are multiple versions of the ROM for any given MY.....so if they check, they better know all of them and have them handy to compare to make that determination. They could just read the ROM header and see if the ECU ID matches but AFAIK all reflashes retain that.
I am pretty sure there's no reflash counter being incremented when you reflash. The only persistent memory on the ECU is the ROM and when you reflash, that is what you're blasting away with the new version so I can't see how they could tell unless there's another mechanism that I don't know about in the ECU that keeps track of that based on the sequence of SSM commands that lead to the reflash....doubtful.
I really, really doubt they can tell. But go ahead and ask them....I wonder what they will tell you