The title pretty much says it -- e.g. the loading screen says Summer 254 BC but in game it's Summer 253 BC. Not exactly game breaking, but I thought I'd mention it in case this isn't known. I haven't checked yet how consistent it is (it definitely didn't happen during my 2.2r Pergamon campaign). In this 2.3 Romani campaign it has been happening pretty consistently since I've started paying attention.