I have seen one that is not distorted.
I don't want to sound like a d!ck, but I've sat in about 12+ Odysseys, and all have had a distorted mirror. I did 5 or 6 trips with the Odyssey to the dealership for various issues, most of the trips are related to the mechanic doing a poor job of installing the rubber window trim. (3 trips were for the driver side sliding door trim), last trip was because they pinched the washer fluid when they did the wipers rod recall, so no fluid was coming out. Anyways, the trips have all been a few weeks appart, and while I wait, I just go around sitting in Odysseys to see the various windshield distortions (I have seen an improvement windshield wise) and mirror distortion. As well as the brilliant fitment of the rear tailgate. Last trip I started looking around the doors for paint leaks/ buildups (have not seen any). Most models I sat in were either EX or EX-L, only 2 tourings and no elites.
The one you sat in without distortion, do you remember the trim? I'm assuming it's the same mirror, just different housing between trim levels, but I'm curious. Also was it recently? I have not been to the dealer for a few weeks now (i probably jinxed myself...)