My apologies, I saw the edit after i posted, actually..
Though as i said, i do find it weird at the same time, that the thumbnail always shows the document (the first page at least) in its entirety - and not just 1/4 page of text.. it's the case for both ipad and macbook...
I know...I find it very odd myself. I have used Pages for many docs with multiple pages and have put the iPad on sleep mode or have gone to another app before coming back to it and the doc shows up.