I think I know that answer to what happened I just want to know what everyone thinks. This is my first time doing graduations so I had more cakes to do than I am used to so I froze my cakes so It would go faster. Well I didn't let one of the cakes thaw all the way it was pretty froze yet, I filled it and frosted it and then put in the fridge and then after a hour or so I covered in fondant and a few hours later I look at my cake and it is bulging at the bottom, so I am guessing that you can't cover a really cold/frozen cake? after it thawed it settled? gosh I guess you live and learn luckily so far it doesn't look that bad but, what a stupid mistake!! So is that what everyone thinks happened?
I've only got the bulging when I don't leave the cake to settle long enough. So I fill and leave it in the fridge over night and then cover it next day. That way I can remove any excess filling coming out between the layers.
I've also read here on CC that some people put a tile or heay book on top and press - I guess that gives the same result as letting gravity work over night.
I've noticed that alot of people say exactly what you said.."after it thawed, it settled?" Yes it settled....BUT the thawing isn't what caused your cake to settle...
Cakes ALWAYS settle. That's just part of the process. This is the reason it's important to wait 12-24 hours after filling BEFORE applying your fondant. You can speed up the process by applying weight (a book, ceramic tile, etc) on top of your filled cake but it will still take some time for the cake to settle.
Also, you should NEVER apply fondant to a frozen cake. A cold cake is okay but not frozen. THis will cause problems of it's own.
Of course after filling I wrap in plastic wrap to keep my cake from drying out. Some even crumbcoat I think for this process.