Quoted from asay:
I've summed up the article for everyone:
skitb (Click image to enlarge)
There's probably a good chance that this is what could've happened.
Most license holders are ok with fans doing one-off items that aren't intended to be made for sale, so long as it's clear that it was unofficial and/or done by a fan.
When you start getting into the actual production and sale of products, fair-use no longer applies. Then you're using someone else's property to create your product and make money from it.
This is like asking to borrow someone's car to make a trip grocery store. Then making the leap in logic that since you have the car anyway, that you can resell everything that's in it--including the spare tire.