Hi Mal,
Bummer. I've not made cams for about a year now, but I have made a couple semi-lactic PC ripened cheeses recently. From my recollections, blue will form if it gets too humid. So, if you're getting lots of condensation in the box, then open the lid a bit more and wipe it down every day if you can. Also, take heart, I belive cams were originally quite mottled with the snow white coating we've become used to being something that was developed in the late 1800s or early 1900s. You're just being more traditional, yah, that's it. A cheese for your determination!
- Jeff