I too am betting you heard a deer blow at you. They can be LOUD sometimes, and they can walk thru the woods without a sound sometimes too. They are typically more quiet than the squirrels here.

On a similar note, I hunt near a house, and when the fan on the outside of the house kicks on, it screeches at startup. GETS ME EVERY TIME!!! Its soooo loud, and I am about 60 yds from it, it makes me jump just about every time. Gets me in the dark too. Its funny, and I know the deer are used to it, so no big deal.

--Jim