It's a bug in a generator.
On thursday we're released version 10C (268). On friday, together with a VPS update, setup of version 10C was mistakenly re-generated, resulting in slightly different binary.
Because internals of setup (updater) are written in a way that it needs perfect sync with our servers, it had to download that binary.
But, because most of the reporting code just compares the versions, it did display 'up-to-date', because version numbers were the same (268 -> 268).
So, this bug cost most of you just 300kbs of download.
sorry for that anyway,