This is interesting in that it will probably stay as an M4.1. It was obviously a deep strike-slip (shear), and shows a magnificent asymmetry in the felt area, shooting to the NE. This is a classic phenomenon for the larger Eastern earthquakes, and why the Hamilton fault is so deadly for Toronto.
They aren't doing solutions for M4's any more, but this is in the upper shearing zone.
Keep on injecting! It's not doing anything.
Update: I hadn't realized that earlier there was an M3.9, with a 6 intensity. Most likely a shallow shear.