Nah, mould on the rind is normal, and in the end, cheddar types are better when they get a coating of mould on the outside (just brush it back every few days). Personally, I find waxing a cheese before a month or two problematic because of whey retention (the cheese gets wet under the wax, and that will ferment). Just cut the rind off when you eat the cheese (wild rinds are rarely tasty in a good way, but they do help deepen the flavour of the interior paste).
But, if you want to keep the wax coating, then it is probably best to just scrap the surface clean, and reheat the wax hot enough so it kills any surface bacteria. That should, in theory, help prevent mould. Wiping with vinegar and sal adds moisture to the surface, and you want that dry before waxing, which just leaves it exposed to get re-contaminated anyway.
- Jeff