This is my third cat which I obtained from Petfinder also. The first cat I had for only 6 weeks ultimately had to be put down due to liver cancer (and over $800 in vet bills).
I immediately got another one from them which turned out to be feral. I never saw it for a week and even searched above the drop ceiling in the basement. Turned out her hiding space was behind my computer which she accessed thru that opening in the back of the desk. I returned her to the cat rescue group.....
Several weeks later I then found P-Squeeky, my current cat, again via Petfinder.com. During warm months I leave the door open to the back deck and she is free to come and go as she pleases but odly enough she will only leave the deck to stalk a bird which might be on the birdfeeder 20 feet off the deck.
I've had her for about 4 years now and she has been great company and never a problem.