It hard to imagine a store that sloppy.
The article also mentions that he released firearms before the background checks had come in. This might not be exactly what it seems. I can't speak for CT, but here in MD we had a period of time when the State Police advised FFLs that since a 7 day waiting period was te letter of the law, they could release a handgun to the customer after 7 days even in the absence of a completed state background check. The State Police later reversed their policy, but not before some FFLs had released handguns with incomplete background checks. (The current wait here is 40-60 days, BTW.)