In my experience, getting spots of mold is par for the course. You can rub off the mold with a paper towel or cheesecloth moistened with white wine or with a combination of vinegar and non-iodized salt. Once the mold starts, expect to see more of it, probably every day.
Just keep an eye on it and keep wiping it off; eventually the rind will harden enough that mold becomes much less frequent. Alternately, assuming the rind is dry to the touch (which it should be after 3 weeks!), you can wax or vacuum bag to avoid any future mold. Naturally, first wipe off any existing mold and allow the rind to dry again.
For some cheeses, you can also just let the mold develop, brushing it down to keep it from getting too far out of hand; this mold will impart additional flavor to the cheese, but most people don't like the moldy rind itself and cut it off when eating the cheese. I don't know if this style of rind is often (or ever?) done with Goudas, but quite common with tommes ...
