I made this icing for some cupcakes last week & fell in love with it, so I made hubbys b-day cake cupcakes in it yesterday afternoon/evening. I put the cake in a carrier since we're not cutting it till tonight, and put the cupcakes in a cupcake carrier, and the icing looks melted, the kitchen is cool, air is on, & it's not to hot outside, so I'm not sure what I did wrong! & my fondant decos are sticky now! Should I have left it all uncovered?

I'm mixing a new batch right now for my cupcakes, the cake doesnt look bad at all. I really love the taste of her icing, and want to use it again in the future!

the fondant can sometimes start to melt in an airtight container.
cant offer any help on the bc, but im sure you could try and pm her too. its supposed to be super resiliant, so it might be you mismeasured something? or the fondant going funny did something to it?
xx

brincess_b is right about the airtight container. I think the moisture from the cake itself gets absorbed into the frosting and fondant when it's well sealed up. I usually just loosly drape my cupcakes with plastic wrap once the frosting has crusted, and my fondant flowers on the cupcakes don't end up soggy. I always use indydebi's wonderful recipe too.