Previous versions of the game were built using a bit of an old version of GameMaker and Steam SDK, but this patch has now updated them to the latest versions.
This should help with compatibility and was necessary for some future features (such as HD fonts). Ideally you shouldn't notice any difference, but there were some changes needed under the hood (in particular with the positioning of text) so let me know if something looks out of whack.
I've also added the old v3.1 patch as a selectable Beta you can roll back to just in case you run into any bigger issues. :]