This can happen for a variety of reasons. The first time I wore Jubilation XXV I got a horrendous musty note, but I tried it again a few days later, putting it on freshly showered skin, and got something that is just wonderful. I'm not sure if it was skin chemistry or if it was my nose becoming more attuned after sampling a wide variety of perfumes.
I'm not sure if it would be musk creating the musty odor from what I see musk isn't in Samsara. The notes listed are, Jasmine, Ylang Ylang, Sandalwood, Narcissus, Tonka, Iris, Vanilla.