I just made my second fondant cake. Just a small 6-inch cake, decorated with a 'winnie the pooh' theme. I have to keep going into the kitchen to look at it. When I went into the kitchen to yet again admire it...to my suprise I found the fondant on the side of the cake had these really large bubbles! Why did this happen?
Im not really sure why but I get them sometimes too. Just take a small needle and poke it and let the air out and the tiny pinhole wont even be noticed.
Did you frost your cake while it was frozen? Did you let the cake rest before covering with fondant? This is what some people call cake farts. I let my cakes rest after filling, before frosting to let the air and gases escape.