If you didn't see any bruising or change in shape to the muscle, and if you didn't feel or hear a rip, there is a chance it was just a major strain. This is something you will have to move forward with carefully. I imagine that a lot of rows, especially free weight rows, are going to cause irritation. Proceed with caution and listen to your body. If you feel discomfort, back off. This could take some time to recover from, so don't make it worse and delay healing. If you think it is a tear, it really wouldn't hurt to go get an MRI and find out exactly what has happened.