Let me start by saying that these are just my observations and should not be taken litteraly but.. I don't know, there might be something here afterall.
I apologise for my English is not my native language and there could be some grammar mistakes.

Ok season 1, it was realesed in spring 2011, and the motto/slogan was 'Winter is coming'. Then in February 2012 there was a thoughest winter in Europe since I don't know when, all Europe covered in snow, I mean I live here, and it was chaotic. There was snow even in Sahara desert, Afganistan and places that almost never see any in the same time as whole Europe was being covered in snow.

Season 2, realesed spring 2012. Motto/slogan of season 2 was, 'The war is coming'. Season 2 began with a comet in daytime and nightime, one lady said the comet means that the dragons are returning, as a persecutor to great war, SHTF if you will xD. Now this year we had one, and we have two more coming, one this month, PanStarrs if that is correct, and ISON later this year. And could we see a war coming soon, there are tensions everywhere between kingdoms of the Earth. That 22. March alliance of nations thing, pope stepping down, comet during conclaves.. I say existing times indeed.

Season 3 is not realeased yet, not the motto or slogan but trailer is realeased. And this is from the opening trailer, intro: 'It's been a long time my old friend. Death is coming for everyone and everything. The darkness that will swallow the dawn.'

I know here are many people that belive the Bible. Revelation of Jesus Christ: beasts, dragon, riders of the apocalypse, comets, starst falling from heaven.. So I thought some of you might like this observation, and it is only that, an observation. I know TPTB like to put some things that are to come in their movies, series and that stuff, so what do you think, could there be something to this winter is coming, great comet that is seen during day and night as a sing of beast/dragon coming and a great war.. I want your thoughts on this, not predictions, just thoughts :)