The red sky is likely going to be story related but I hope it happens often and not just once. It looks seriously cool! I'm sure since Luna has the power to stop the plague of stars (I assume this is related) we will be seeing it often.
Well they said the nights will get progressively longer, i think the red moon will be the final stage of this process but really late into the game when everything has gone to shit and you just have to slay the final boss, kinda like the looming Meteor in the FFVII overworld.