Hey, I never knew that rosy boas could musk either until I had a bunch of neonates to probe (determine genders)- OMG I thought I was going to hurl! It sure didn't take much either!
Some kinds of snakes are more prone to musk- when rat snakes are properly "socialized" they don't do it either. King snakes are more prone, since it's their typical & only defense as hatchlings.