They mentioned this on the podcast, apparently it's due to the publisher in the EU changing from the American to the UK one. They need to correct (ahem) spellings and change the cover. But... Firstly, I think everyone in the EU can read and understand virtually all the differences between American English and British English, and the cover art is fine for the UK, so what's the point? Secondly, I can order the UK hardback, so why can't I order the UK Kindle version?
Oh well. It sounds like either the uk prerelease was a bit premature, or maybe the pre-ordered have been successful enough to warrant a UK/EU version.