Oh my! I didn't mean to portray myself as any sort of authority on the subject.
I'm merely sharing my experience. Okay, here goes:
Handymama -- I've made a red with black trim purse and I've made a light green and white purse. I put the black one in the frig only one night and had no problem with bleeding -- it did condensate but I didn't touch it and there was no bleeding. If I had touched it I would have had an Alice Cooper thing going on with that purse (which thankfully didn't happen -- not that Alice isn't totally cool!)
I always cover the fondant cakes loosely with plastic wrap in the frig. I've had fondant overlays bleed onto buttercream before but that's because buttercream is considered a liquid and that can be a big problem if using the darker colored fondants. I also use both Satin Ice, Pettinice, homemade marshmallow fondant and a white chocolate fondant (recipe from Jennifer Dontz.) I've had no problems with any of them. If your black fondant is touching anything that will create a problem with bleeding, make sure it's not touching anything and you should be fine. Hope that helps some!
Tinygoose (what a cute name by the way!)
-- If you look in my pix, the towering inferno cake, Edie's shoe cake and the Gilda's Club 10th anniversary cake -- all three of those were transported chilled and the pix are taken onsite after setup. I prefer to transport them chilled to reduce slipping but that's a personal preference. If you give the cake a Crisco rub and then chill it, it won't crack when it comes to room temp and again don't touch it while it's sweating. This also makes the fondant pliable when they go to cut it and eat it. Hope that helps!