Question for those who have GM DOD/AFM experience.

So I bought a 2011 Escalade with 107k miles Saturday. I drove it to work and around the base for a bit and then eventually drove home with no noises. I let it sit for about 45 minutes and then started it up and heard lifter tick. I pulled the valve cover and the rocker is flopping like a fish. My question is, do you immediately suspect damage to the cam after starting it and idling for a minute or so or did I catch it at the right time? Asking for opinions before tear down if I’m guaranteed to buy a cam or just the lifters and gaskets. Will post videos in comments.