Bethesda's Pete Hines explains, "That is the error you get when you try to enter a code too many times (unsuccessfully). Most likely because they were entering the code yesterday before the packs were live on PSN. The user just needs to wait 24 hours and enter it again. Once you download the content it will work with any existing save game."
The PSN needs to update on Tuesday before content becomes available. In the case of pre-order DLC bonuses for newly released games, it's best to wait until the update occurs on launch day and then try using the code you received.