It's happened to us multiple times and it's always a competitor trying to get out listings taken down. They look for any data fields on a listing that haven't been filled out by the seller (most likely because they didn't seem relevant to the product) and then they'll add words to these fields that the algorithms will pick up and cause the listing to be suspended. You can try to prevent it by making sure you are Brand Registered and uploading a flat file containing a value for every single field. Amazon will eventually reactivate listings that are attacked in this way but you can lose a lot of time and money waiting.