ALWAYS check the filter boxes, no matter the source. When I sold Auto Parts (holy crap, was that really 20 years ago!??!) you would be amazed how many Motorcraft, Fram, Delco, and Casite filters came from the factory missing the o-rings. I would personally find about one a week working the floor, more often if I worked the register. We had a store policy that we were to open all oil filter boxes and check for them.
Since I've always been in the habit, I still do it today. I found a Motorcraft filter at the Ford dealer for my wife's car that was missing the o-ring just a couple years back. I found another one on the shelves at the local AutoZone just a few weeks later. I found still a third filter that had the WRONG THREADS in it!! (It was an FL-500S that wouldn't thread on properly)