Well Gang,
First off, while it "could" be possible that the vent all of a sudden clogged up, I'm not sure it's likely. The reason I say that is, those seals have been fine for well over 110K miles. Then, for them BOTH to go bad at one time, due to a vent that clogged while sitting in a dormant state, well, who really knows?? And, based on the OPs statement that it's really cold there, wouldn't that preclude that there should be NO PRESSURE built up inside that axle housing, during its rest period inside the barn? But, even with zero pressure inside that axle housing, since the oil is constantly against the bottom side of those seals, I guess it could just happen.
If the barn was really hot inside, like during a really hot summer, and this situation happened then, I think I could see that, if the vent had clogged, the built up pressure would have no place to go but, through maybe both wheel seals. Just a thought. But, again, stranger things have happened. We'll have to see what the OP does.
Scott
