Kenny, do you have a photo of your razor? My first thought is that you had water and/or lather in the scales, which, when you closed the razor, then got on the blade.

Also, the question about where you store your razor is an important one - if you left it in a humid place, like the bathroom, that could do it too.

Extra protection, like Utopian's method, is never a bad idea, but if you are careful in caring for your razors, it's shouldn't be necessary.