You forgot to mention the Nymeria re-union. That was heartbreaking, but I'm sure she'll be back to protect Arya though!
I wouldn't make too much out of it — it could just be the writers & animators giving a nod to the fact that the winter has come. It's not easy for the entire ocean to freeze, is it?
"I am not sitting by the fire knitting while the men fight for me... and I don't need your permission"
Lyanna Mormont has easily become my favorite character after this episode!