This is the first time I've had any issues with my knees at all. Usually if I get any pain it's in my right foot. I suspect that my toebox may be too wide for my Northwave MTB shoes.
My knee is feeling tons better every day, so I'm optimistic that it's just a pull and not anything I'll need surgery for.
I think that the injury may have been caused by a variety of factors: taking a week off, pulling the kids around on a toboggan, and one lap (though that shouldn't have done it even though the skates were a craptacular fit) of ice skating. And I'm getting older. Bummer!