It well be an approaching season, but I think I would try and curb the habit quickly anyway as its not a good way to express herself and could be a way of her getting confused about her status in the household? Is she quite a confident dog normally?
I had the most gorgeous labrador many years ago who did get confused and started to get a bit snappy, we took some advice and just did some basic signs, in doggy language, that we were in charge, not him, he was much much happier once he understood he didn't have to take leadership on his shoulders.
My inspiration came from a book called the Dog Whisperer by Jan Fennell who was very much in vogue at the time and I still think is great. There were 7 basic rules, I can't remember all of them but the ones we used were ….
Never let the dog get higher than you, so for a little bit sofas, chairs, etc are out of bounds - top dog always gets the best seat.
Never let the dog go through a dog before you, you are the leader!
When you feed your dog, always pretend to help yourself to a bit of his food first - in a pack the lead dog eats first and they the subservient ones eat later.
When you go out of the door don't say goodbye if you are leaving your dog, or greet immediately when you come back - you have the right to come and go as you like and don't have to ask permission.
If you are interested the book is still available and is a very interesting and good read.
http://www.amazon.co.uk/The-Dog-Listene ... +whisperer