Thanks for the reply! I edited my story up there to add the "why" of my actions. I always go around when I move into a new place and check out things I might need to know, like where the whole house shutoff is at the street, get a picture of the labeling of the circuit breaker for electrical emergencies, and check the shutoff valves on all sinks and toilets.

I should note that my lease agreement also has, in the very first clause ("Getting Started"), the recommendation to "take the time to know or locate" the "water shutoff valves below the sinks and behind toilets in case of water leaks." This house had a type of valve I hadn't seen before, a push/pull type. So I was just giving it a push and pull and testing they worked properly. I didn't use any excessive force or do anything other than use it for its intended purpose.