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You said that one side is drying out... is the other side still moist?
Assuming that the cheese is equally dry all around, you should take the size into consideration.
A small cheese, or a cheese with a large ratio of surface area (ie a large thin wheel), will dry out much more quickly than a large one, and I think should be waxed sooner rather than later to avoid overly drying out the cheese.
If the cheese is particularly large, I would imagine that there would be enough moisture inside to prevent this from happening. In fact, you'd probably want to air dry a semi-hard cheese like gouda longer to ensure that it is fully drained/adequately dried to reduce the chances of excess whey weeping out or causing spoilage problems during aging.
I am not an expert on gouda though. Can anyone else back me up on this?