Ok, first off, the difference was noticed between two DIFFERENT cars. I had just handed over my 33k Vin and sat in the loaner which is a 38k Vin. I had no expectation for a better seat, since I wasn't expecting it the exist at all. So no, I would not say it is psychological at all. Also if your Vin is higher than 38 I would say that you have the newer seats. Since you are 30k, I don't know that I would believe what they told you. Find someone with a newer car and have a seat and see if you feel a difference.
Second I got back word about the mod they are going to do to my car. It is the fix that I believe I had heard others mention before, which is that they are changing the springs in the seat to make them more comfortable. The service tech was far more detailed about what and how they we modding the seat, but offhand I can't remember the exact details. So, modding current seats and NOT replacing them.
Finally, they were not sure if there would be another fix coming down the pipe or not. The service tech said that: one, many times we (owners) hear of things before they do since a lot of change come down the pipe without them knowing about it. Two: there were rumors going around that they might be doing a second seat that would be more comfortable. He suggested the terms a "sport seat" and "comfort seat". Again, just rumors he had heard, nothing official yet.
In Elon we trust, I suppose... Hopefully we still see this come. But I will say, those with a Vin in the 38s or higher should have a much nicer seat already!