I believe that is just salt deposits expelled from the nostrils. That is normal, many animals including humans, expell excess salt that way, however humans do it much less because we lose so much salt by sweating.
Some people think it may be calcium build up, but it's a myth.
Here's a quote from a veterinarian on the forums:
Ferretinmyshoes: "Some reptiles have a salt gland near the nose to get rid of excess salts from their diet or water source. This causes crusty white buildup around the nose sometimes. It is NOT excess calcium (a common myth). The salts are primarily excess sodium or potassium with just the tiniest bit of calcium sometimes. Do not change your calcium supplementation as the buildup is completely harmless and not a cause for concern. Check your water for sodium content and you may need to use distilled water. If the crusts bother you or your cham then gently wipe them away with a moist q-tip."