Relying on internet forums for medical diagnosis is a sketchy proposition at best, and there's not enough information here for me to recognize an issue. Maybe one of the other coaches will chime in. I note several incogruties with a torn infraspinatus: primarily that the pain was sudden in onset, and only on a working weight set. My entire experience with torn muscle is that ANY movement was painful. But YMMV.
And we can't see your squats / BP from here.