This past weekend I made this cake.
http://www.cakecentral.com/gallery/i/3341379/rn-cake

 I just got an email from her saying while the cake was delicious the fondant accents on the sides slid off and messed up the buttercream frosting.  She had it in air conditioning (72 degrees).  I based this cake off pictures I have seen so I know many other people have done it so I'm not sure why it happened.  After further investigation she said it was the stethoscope portion that slid, the bandaid on the side only slid a little and wasn't noticeable.  I can see maybe the stethoscope was too heavy...but the bandaid?  I don't think that would slide. And the stethoscope was already almost to the bottom of the cake already so the tube portion would have had to break to slide down.  Which she did say it was the tube part that slide.  I can't figure out how since it was so far on top of the cake, not the side.  I am wondering if the cake had a rough transport or was in the car for awhile.  Please tell me what you think.  I already offered her a gift certificate for the amount of the fondant decor.  She's not upset but it definitely makes me look bad.  Scared to make this cake again, but I think it will be popular.  How should I do it in the future?  I made a cake the next day with some heavier fondant accents on buttercream with no problem...

Hmm...I don't see why it would slide off unless like you said it was left in the car long and caused it to sweat from the heat. What did you use to stick it on? Just a dab of water? Sometimes if there is to much water when placing it on causes it to move around and slide off.  Some times I  use powdered sugar mixed in water as the adhesive to get a stickier grip. But again watch how much water is being put. That's the only thing I can think of that could have gone wrong. Best of luck! Cute cake. 

Thanks SoniaMT!  It was on a buttercream cake so I applied it to the buttercream before it crusted over.  So no additional water.  I can't think of anything that would have caused it either.  It is all seeming a bit odd to me now.  They were camping so the cake was in the air conditioned camper.  But it takes some time to set up a campsite so I'm thinking they left out the part where it was left for awhile.  Not sure if I'm getting the whole story, but I gave a gift certificate anyways just to avoid any issue.  

Ohh ok...yea I'm sure the butter cream must have been left out long enough to cause it to melt. Specially if they were out camping. Don't stress....sometimes customers expect cakes to be perfect under all conditions which really isn't the case. They have to understand that the climate in which the cake is in can cause changes in the cake. 

Thanks.  I told her how to store the cake and she made sure to tell me it was in air conditioning but I'm sure she didn't add, or think to add the fact that it had to have sat out for awhile before being put in the camper.