I shot a deer on a cold day - about 25 deg F. Aged it a couple days when the temp never got above freezing. Put it right in the freezer. When I cook some of it, it smells just a little sour. I've never had this experience. I did not see any signs my bullet hit the rumen. The smell disappears after it's cooked a little, but I'd rather not have it since my crew isn't that wild about game. Any idea what it is I smell and what I can do to do away with it before I cook the venison? Thanks.