I'm finding it hard to believe that moisture and steam have much to do with that pads failure. Please remember, the pad started to show concave BEFORE it was ever rinsed out with water. Now the heat build up may be a factor, but not moisture.
I think it's also worth adding, because the Flex is a forced rotation machine, we have often noticed that the panel of a car being worked on will become more warm to the touch after using my Flex than after using the Griot's. So it seems to me that I would be generating the most heat, doesn't it?
For the record, I didn't clean my pad until I was done with my half of the car. There was very little build-up of product on the pad which you can see in the pic.
I still think he got a bum pad.