Return of Shadowmere

If you've played Oblivion, you understand the impact that Shadowmere had during the game. Now, I have never even used a horse in Skyrim, but when this happened:

I damn near shit myself with joy. 

The only thing I don't understand is why Shadowmere is a "he" in Skyrim but a "she" in Oblivion. Age is not a factor, as Shadowmere is a demon horse and emerged from a pool of bubbling tar. I'm not interested in logic at this point though.