No changes that I know of. I think there was a slight tweak to the mapping for new Euro immissions but that was before the Zed even made it to the UK. Perhaps the MY2010 model had another tweak. I've heard all sorts quoted, 331PS, 332HP, 328HP, 326HP. I think its all down to someone not converting it properly or taking actual numbers they've somehow measured.
I wouldnt worry about it, its not even 1% power difference! Plus, get a exhaust and remap and you're laughing, 20HP+ easily (upto 40HP if you get decats too!)