They released the firearm to you after checking their paperwork and you paid for it, so you took possession legally. If they want you to correct their oopsie so the boys from BATFE don't spank them, you can do it at your leisure or they can send a manager to you to take care of it.
I no longer patronize Cabela's because of their dropping their "World Class Guarantee" where you could take anything you bought from them and return it if you were not happy with it. For decades, I bought all my outdoors gear from Cabela's, until I tried to return a pair of hiking shoes because they got slippery when the soles got wet. One of their CS Supervisors berated me for trying to return the shoes after I had worn them. When I asked if that was a problem since Cabela's had an absolute guarantee on all of their gear, she told me they had discontinued the guarantee because they couldn't make any money with a guarantee like that. I smiled, left the product, and called the credit card company to cancel the charge. I no longer shop there, and encourage others to do the same.