I wouldn't assume it happened in the gym. Bodybuilders are always tearing stuff doing mundane things like arguing with an ex with a car door in the way. Flex could have gone water skiing or something and torn it.

With regards to working out on a vacation, I like checking out a local gym or even a hotel gym and trying new machines. Good place to checkout the local booty too. Wouldn't bother with a serious workout or anything, just get the blood moving. Maybe do that twice if I was on a week's long break.

Also I'm past the stage of thinking soreness after a workout is a good thing. Those couple of workouts during a vacation keep the body in check for when I get back into it after the break.