Jim-
Welcome home!
Knarf-
I found the same thing, except I got a 2” thick mattress pad-thing from Ikea to put on top. Best bed I’ve ever slept on, as far as I can remember.
I had to use my hole saw to access the fill spout (or whatever you call it).
And I will have to put a central spreader 'cause the frame is bending a bit.