It happened with all civs I had war with - Vikings, Zulus, India and China. I also noticed that I still have an embassy (I can see tiles at their capital) even when at war (actually embassy disappear like it should - the option to establish them becomes available in diplo screen, but tiles stay revealed all the time, even when at war). And I only increased PEACE_TREATY_LENGHT to 30 (I forgot what's the basic value). This, together with my own eternity settings (it's 1815 AD and 2724th turn) gives me exactly 132 turns of ceasefire.
And I don't remember why exactly, but I recalculated because I did some minor changes to some xml file few days ago. It changed nothing, both before and after that the situation was still the same.
Well, it's not that it's a gamebreaking bug because it's still the best mod out there, but it'd be nice if I could fix it in my future games somehow.