Makes sense, Arizona resident and have not had this issue.An updated to my seat problem.
I noticed the issue was really related to the weather temperature. We got about 17C right now after the long cold winter below 0. The cushion seems absorbing the heat and expanded back to the original sharp. Just a very little bit depressed feeling when you touching on it. Not quite noticeable from visual look. It was exactly what the service guy told me last time it would be better during warmer weather. So it is 95% resumed.