35 page extract from a Neal Stephenson article in my Pages for iCloud beta...

Just signed in to the Pages for iCloud beta for the first time only to find what appears to be a 35 page extract from an article by Neal Stephenson entitled "Mother Earth Mother Board" saved in my account. I've never seen or touched this document before and I have no idea where it came from. The document is dated 1 May 2012, 11:00PM (suspicious?). I googled the first paragraph and found a full version of the article here: http://goo.gl/izX3C

What on earth is going on? Am I seeing a document from someone else's account? Anyone else come across this?